Partner diplomacy is an important force supporting China's deep participation in the international economic cycle in the post-epidemic era,and profoundly impacts the"going global"strategy of Chinese enterprises under the new development paradigm.Combining the theoretical analysis and empirical results of the cross-border M&A data of Chinese enterprises from 1993 to 2019,this paper explores the mechanism and the driving force behind the evolution of partner diplomacy that propels Chinese enterprises to"go global".The study found that:(1)For every level of partner up-grade in diplomatic relations,the number of completed cases and the willingness of Chinese companies to engage in cross-border mergers and acqui-sitions increase by about 3%~4%.This driving effect remains after considering endogeneity issues,changing models,and adding more variables.Robust;(2)Mechanism test found that the essence of partner diplomacy's driving effect on Chinese enterprises'cross-border M&A is essentially the promotion of institutionalized bilateral economic cooperation,achieved through three intermediary paths:rule improvement,high-level exchanges,and cultural integration;(3)Heterogeneity tests found that partner diplomacy has a stronger effect on the effectiveness of cross-border M&A by Chi-nese firms in host countries that are not part of the Belt and Road region,have BIT agreements with China,offer more market opportunities and ex-hibit lower levels of political mutual trust.(4)The extended test indicates that the three types of partnership upgrades-namely tier upgrading,qual-ity deepening and mechanism creation-have an increasing effect on enhancing the effectiveness of cross-border M&A by Chinese enterprises.This suggests that upgrades in partnerships can strengthen the binding and enforcement power of institutional arrangements,leading to a shift from a"consensus-driven"to a"mechanism-driven"model of partnership cooperation.