The influence of international science and technology organizations determines the play of multilateral cooperation and the realization of their social missions. Establishing the evaluation index system of the influence of international S&T organizations helps judge the influence level of different international S&T organizations and provides a reference for promoting Chinese researchers to work in influential international S&T organizations. This paper used the literature research method, bibliometric method, and expert interview method to construct an evaluation index system for the influence of international science and technology organizations from three aspects of academic, social, and global governance influence, including 3 first-level indicators and 12 second-level indicators. The study assigned weights to the indicators with the help of the Delphi method and used objective data to empirically analyze 19 international scientific and technical organizations in the geology category. The results show that the evaluation index system and quantitative formula designed in this paper are scientific and reasonable, with high operability and practical application value, providing an effective reference for promoting our scientists to serve in international science and technology organizations and driving the development of international science and technology organizations led by China.