Social stability risk assessment of major projects is to prevent and resolve social contradictions and govern the social risks. The subjects of social stability risk assessment run through each link of stability evaluation. To know the categories and characteristics of stability evaluation of subjects clearly and clarify the relationship types among different subjects in the process of stability evaluation are further perfecting stability evaluation of the governance structure and evaluation effect. On this basis，this article selects 92 texts including documents and reports of major projects stability evaluation as the sample. The content analysis methodology is used into basic categories and main characteristics of the main body in stability evaluation. Then，the social network analysis methodology is used to explore the structure of various kinds of subjects in evaluation in different relationship types of the network. The main conclusions are as follows：① The basic type of the relationship between stability evaluation of subjects is cooperation relations which can be further subdivided into three sub relations：organization and coordination，supervision，and responsibility relationship；② Though the pattern of“power-responsibility”has been initially formed，the mechanism of accountability with it needs to be further improved；③ The network governance patterns among subjects is still given priority to the“government's leading network”，and the public supervision and participation need to be strengthened.