Abstract: In the process of promoting the reform of government purchasing services in an all-round way, the construction and improvement of the positive interactive development relationship between government purchasing services and social organizations determines the success or failure of the reform of government purchasing services and the cultivation and development of social organizations. Therefore, in the new situation, it is necessary to analyze the dynamic mechanism and internal mechanism of the interaction between government purchase service reform and social organizations, which is the decisive factor affecting and restricting the interaction between the two. Generally speaking, the interactive development of government purchasing service reform and social organizations at this stage is a clear response to the reform of administrative system and the construction of cloudy public service supply system, as well as the coordination between financial capacity and the responsibility of public service supply. At the same time, it conforms to the internal motive force and external conditions for the development of social organizations. Based on the internal logic of the reform of government purchasing services and the basic strategy of the development of social organizations, the decisive factors restricting the construction and improvement of the positive interaction between the two are mainly the transformation of government functions, the public financial system, the system of institutional norms and the level of market-oriented development.