A four-stage online collaborative learning approach to supporting teachers' professional development was proposed and described in this paper. This study investigated primary school teachers' interactive networks and social knowledge construction behavioral patterns in online collaborative learning activities. The subject of this study was 83 primary school Chinese teachers who were participating in a structured online professional development program that was 6 months in duration. By combining social network analysis, content analysis and lag sequential analysis, results showed that interactive networks generated in two rounds of online collaborative learning activities were low reciprocal, and loosely connected with a low cohesiveness. There was no significant difference of behavior distributions between core and peripheral members. Moreover, teachers' social knowledge construction behavioral patterns presented different characteristics in different rounds of activities. In addition, this study identified certain problems in teachers' online learning. Finally, some implications for the design of teacher education programs, limitations and further research plans are proposed. •A four-stage online collaborative learning approach was proposed.•Interactive networks were low reciprocal and loosely connected.•There was no significant difference of behavior distributions between core and peripheral members.•Social knowledge construction behavioral patterns presented different characteristics.