Abstract: With the leapfrog development of financial technology, the third-party payment institutions due to their diverse, flexible, safe and swift serving model is rising rapidly in China’s payment market, posing an unprecedented challenge for the bank’s dominant position in finance. As the most vital payment service providers, their businesses keep crossing and merging, being complementary to each other while inevitably conflicting. To properly understand the coopetition mechanism between the third-party payment institutions and commercial banks is conducive to promote the stability of cooperative relations, prevent the the financial risks, improve innovative development of national financial system. Chinese third-party payment institutions and commercial banks are taken as the research objects, related annual reports and forecast data are adopted, the idea of evolutionary game theory and two-layer network evolutionary game simulation methods are drawn on, and the evolutionary laws of coopetition between two types of enterprises and the impact of related factors on evolutionary stability strategies are analyzed. It is found that the evolutionary stability strategy of third-party payment institutions and commercial banks are uncertain, the increase of cooperation benefits, the reduction of cooperation cost, the rise of default penalties and the rationality of benefit distribution will help to improve the ratio of cooperation between the two types of enterprises, and promote the evolution to be cooperation-dominated. Detailed research shows that the two types of enterprises possess significant heterogeneity, third-party payment institutions are more sensitive to changes in related factors and have lower requirements for benefits. The income gap among enterprises is obvious. Large and powerful third-party payment institutions and commercial banks can obtain higher cooperation benefits and more opportunities for coopetition, while small and medium-sized payment institutions and banks cannot obtain ideal benefits from coopetition. The use of the evolutionary game model of two-layer complex network overcomes the realistic defect of individual homogeneity in the previous evolutionary game model, and analyzes the cooperation income of heterogeneous individuals in coopetition. At the same time, the research points out the development trend of the relationship between the third-party payment institutions and commercial banks in the future, which to some extent enlightens enterprises of various types to choose the optimal strategy.

Key words: third-party payment institutions; commercial banks; coopetition game; double-layer network