Model-based systems engineering (MBSE) with SysML has become one of the best solutions to the system design of complex systems, which usually requires the collaboration of different disciplines. Web-based collaborative modeling method looks like a prioritized option because of its advantages such as “light” client, convenient maintenance, and high model reliability. In this study, we propose a web-based collaborative SysML modeling method for MBSE. First, the architectures of asynchronous and synchronous collaboration are given. Then, some key technologies for both collaborative modes are discussed. Finally, a case study is given to demonstrate the effectiveness of the proposed method.