Realization of e-business is based on business process management system (BPMS). In BPMS there are a large number of event logs recording the performers and corresponding activities. Team organization structure is so flexible as to be more suitable for implementation of e-business. However the existing organizational structure modeling methods are difficult to model team structure. This paper design a modeling method of role-based team organization structure based on event logs from BPMS. Usually if the role of performers is similar, they can be classified as a same team. This method analyzes activities type and activities frequency of different performers in the event logs in order to judge their role similarity. Firstly, a PA (performer-activity) diagram is designed to describe the relations between different performers and activities; secondly, the role relation mining rules are designed; At last, the measures of the role similarity among performers are designed based on which a team organization structure can be modeled.