In order to improve the knowledge diffusion effect in Open Source Software Community (OSSC), we built a mult agent-based modle to simulate the whole process of knowledge diffusion in OSSC. First, by analisying real OSSC, a open source software community model was built. Second, mechanisms such as knowledge diffusion mechanism, partnership selection mechanism, knowledge learning mechanism and knowledge spillovers mechanism and sever collabortion mechanism were given. Further, by using multi-agent modeling tool and MATLAB software, the current research modeled knowledge diffusion in OSSC and investigated the effect of members’ knowledge distribution on the performance of knowledge diffusion. Results show that higher initial knowledge variance in OSSC knowledge diffusion process would lead to higher knowledge efficiency, fewer knowledge diffusion path, and lower equity.