Objective  To analyze internal social capital elements of social organizations participating in AIDS prevention and control from the perspective of meso-social capital for promoting the development of internal social capital of relevant organizations.

  Methods  With multistage random cluster sampling and a self-designed questionnaire, we conducted a survey among 211 social organizations engaged in AIDS prevention and control in 18 municipalities/prefectures of 8 provinces with different AIDS epidemic intensity across China during August – October 2015. SPSS 18.0 was used in data analysis.

  Results  The results of univariate and multivariate analysis demonstrated that influencing factors for different internal social capital elements of social organizations included: (1) an organization′s establishment duration and the number of different types of target population for trust factor; (2) variation in the number of organization members for common language and vision; (3) item and number of AIDS prevention and control domains for informal network; (4) an organization′s establish-ment duration for formal network; and (5) the number of target population and funding resources for support factor.

  Conclusion  There is a certain amount of social capital within the social organizations engaged in AIDS prevention and control in China but the internal social capital differs by regional AIDS epidemic intensity, social capital factor, and specific factor item.