[Purpose/significance] The social co-governance model of public information services will be beneficial for improving the supply structure and the quality of public information services. However, like the government's single service model, a series of risks may arise in the operation of social co-governance of the public information service. [Method/process] The article analyzes the types of risks and their causes, including the risks of fragmentation, deviation from the publicity, the choice of participants, responsibility deconstruction and service security. Finally, countermeasures are proposed from the aspects of establishing a holistic governance mechanism to deal with phenomenon of fragmentation, clarifying the government responsibility and accountability of public information service risks, judging the sources of security risks in social co-governance, and focusing on controlling new information security issues. [Result/conclusion] It is believed that the above methods and processes can effectively control the risk of co-governance of the public information service and expand the positive effect of co-governance of the public information service.