Abstract: Open Source Software is a specific case under the phenomenon of Distributed Innovation, which knowledge sharing is the essence and core of OSS. In this research, the author would like to give a quantitative analysis on the core factors and mechanism of knowledge sharing in OSS projects with 403 valid questionnaires. In OSS projects, distributed innovation affects the shared knowledge among the participants and then influences the performance of OSS projects. Developers and users are the two main bodies. Developers have an effect on shared knowledge (medium variable) through Participative Motivation, Social Networks and Organizational Culture (independent variables), while users will affect the shared knowledge through User Innovation (external variable)，and shared knowledge will influence the performance of OSS projects (dependent variable). The money incentive has no significant relationship with Participative Motivation which broken down the existing cognitions, while Social Network has the greatest effect. Compared with technical ability of core members, management ability has more impact on knowledge sharing. It is suggested to encourage the participation of users in the collective intelligence of open source software projects.