Demand Bus System, a new public transportation system, is expected to be a convenient service for special transportation demands to solve more and more serious traffic problems concerning metropolises as Shanghai. Under this background, this paper focuses on evaluating the usability of the demand bus system rather than on the algorithms as the previous researches did. As a useful evaluation tool for achieving this objective, Multi-Agent Based Simulation is used to obtain a better understanding of such system in particular when lacking real applications for a large scale. By using the participatory solution, we propose a multiagent simulation framework to include domain experts, stakeholders, system users, as well as computer scientists to build and modify the computational model directly. The implementation of the prototype system shows that it is easy to build such system from scratch to mega by this mechanism. Initial analysis shows the demand bus system is a convenient service supplement to the fast transportation for community in Shanghai.