1、 Introduction

This article introduces the background and importance of the Lancang Mekong Cooperation, including its role as an important region for China to participate in international regional cooperation, the establishment of the GMS, the proposal and formal establishment of the Lancang Mekong Cooperation, as well as its key cooperation in areas such as connectivity, production capacity, and cross-border economy. At the same time, it is pointed out that existing literature mainly focuses on the legal basis and water resources cooperation of the Lancang Mekong Cooperation, and there is relatively little research on how the Lancang Mekong Cooperation affects China's investment in countries within the region. This article will use data and statistical modeling to explore this issue.

2、 Research Review and Theoretical Basis

The Lancang Mekong Cooperation is a regional economic cooperation mechanism among countries along the Lancang Mekong River, with sustainable economic and social development as its core. The economic and trade cooperation between China and Mekong River countries has achieved remarkable results, with harmonious and harmonious relations, mature cooperation and strong development momentum. The scholars discussed in depth the economic and trade cooperation between China and other countries, especially the development prospects of the Lancang Mekong cooperation mechanism under the "the Belt and Road" initiative. The Lancang Mekong Cooperation not only promotes economic development, but also enhances political mutual trust and elevates China's national image. To achieve coordinated development of the Lancang Mekong Cooperation and the Indochinese Peninsula Economic Corridor, and provide experience and reference for sub regional cooperation. However, the Lancang Mekong Cooperation faces both opportunities and challenges, requiring a change in mindset, methods, and entry points, and an increase in investment.

3、 Research hypothesis

Analyzed the positive impact of the Lancang Mekong Cooperation mechanism on regional development and cross-border investment. The Lancang Mekong Cooperation provides investment opportunities for multinational corporations, promotes cooperation in infrastructure, energy, agriculture and other fields, attracts funds and technology, and promotes local economic development and industrial upgrading. Collaboration can also help reduce investment risks, improve the predictability and stability of investments, and promote sustainable development. In addition, the Lancang Mekong Cooperation has optimized the investment environment in the Mekong region and enhanced its investment attractiveness. Based on this, hypothesis 1 is proposed: the Lancang Mekong Cooperation mechanism has a significant promoting effect on cross-border investment within the region. The "Five Links" policy of Lancang Mekong Cooperation (policy communication, facility connectivity, trade facilitation, financial integration, and people to people connectivity) is a key factor in promoting the deepening of cooperation and has an important impact on Chinese enterprises' investment in the Lancang Mekong region. In terms of infrastructure connectivity, the cooperation between the Lancang Mekong countries in transportation, energy, communication and other fields provides a foundation for economic and trade cooperation and cultural exchanges. In terms of policy communication, the Lancang Mekong countries have laid a political foundation for cooperation through high-level dialogue and policy coordination. In terms of financial integration, the Lancang Mekong countries have strengthened financial cooperation, promoted capital circulation, and reduced financing costs. In terms of smooth trade, the Lancang Mekong countries have eliminated trade barriers, improved trade facilitation levels, and deepened industrial cooperation. In terms of people to people connectivity, the Lancang Mekong countries have carried out cooperation in education, culture, healthcare and other fields, promoting cultural exchanges and people to people connectivity. Hypothesis 2: The Lancang Mekong Cooperation mechanism affects China's outward investment in the Lancang Mekong region by influencing the degree of the "Five Links".

4、 Model Methods and Data

This paper introduces the application of the Difference in Differences (DID) model in evaluating the impact of the Lancang Mekong Cooperation mechanism on Chinese enterprises' investment in Lancang Mekong countries. The model includes annual and national fixed effects, with the treatment group consisting of investment data of Chinese enterprises in the Lancang Mekong countries and the control group consisting of investment data in other Southeast Asian countries. In the model, the dependent variable is the logarithm of the number of green investment projects, the independent variable is the interaction effect after the proposal of the Lancang Mekong Cooperation mechanism, and the control variables include the host country's economic scale, per capita income, GDP growth rate, and institutional variables (legal level, government efficiency, regulatory quality, and corruption control). The data sources are the World Bank and the Global Green Investment Database, covering the period from 2013 to 2023, with a total of 1746 sample observations covering 9 Southeast Asian countries and regions.

5、 Empirical results and analysis

The impact of the Lancang Mekong Cooperation mechanism on Chinese enterprises' outward green space investment was explored through empirical analysis. The benchmark regression results show that the Lancang Mekong Cooperation mechanism significantly promotes Chinese enterprises' investment in member countries, both in terms of project flow and stock. The effectiveness analysis of the double difference method, including parallel trend testing and placebo testing, validated the accuracy and credibility of the baseline regression results. Heterogeneity analysis found that the Lancang Mekong Cooperation mechanism mainly promoted investment in Laos, Thailand, and Cambodia, while its impact on investment in Myanmar and Vietnam was not significant. Mechanism analysis explores how the Lancang Mekong Cooperation mechanism promotes Chinese enterprises' outward investment from five dimensions: policy communication, trade facilitation, financial integration, facility connectivity, and people to people connectivity. The results show that the Lancang Mekong Cooperation mechanism has played a positive role in all five aspects, verifying the validity of hypothesis 2.

6、 Conclusion and Implications

Summarized the impact of Lancang Mekong Cooperation on Chinese enterprises' outward investment behavior. Research has found that the Lancang Mekong Cooperation mechanism has significantly increased the scale of foreign investment by Chinese enterprises in Lancang Mekong countries, especially in Laos, Thailand, and Cambodia. The cooperation mechanism has promoted Chinese enterprises' outward investment through five aspects: facility connectivity, policy communication, financial integration, smooth trade, and people to people connectivity. The policy implications include: facility connectivity to facilitate foreign investment, policy communication to build a solid investment foundation, funding support through financial integration, trade facilitation and foreign investment complementing each other, and people to people connectivity to create a favorable investment atmosphere.