The aim of this study is to investigate the key factors, process and outcome of the effect on team knowledge sharing. The author collected the whole process of team knowledge sharing through multiple data sources. The study observed and analyzed each three teams of high performance from online game team and management decision team as study samples. The result indicates that knowledge sharing will be influenced by the following key factors: leadership, the overall goal of team and team integration. Therefore, the leader depends on the conditions of team members to choose appropriate manners that let them share knowledge actively. In addition, as a team, they should set up a clear and specific goal that team members can follow. In order to achieve the goal, members will take the team learning through knowledge sharing. All members should integrate well and share knowledge actively to accomplish the goal of team. The process of knowledge sharing has two stages: In the initial of a team, members will accumulate experience by learning the knowledge of task. Later, they will get into the stage of group-orientated knowledge to use and share the tacit knowledge. Finally, knowledge sharing can improve the team performance, increase the self-efficacy of team members, and make the members closer.