Since the bus is regarded as the one of the most public transportation systems, research on the safety and facilities of the bus has been increased actively in recent years. In this paper, we concern the design of the bus door mechanism that is composed of many linkages and actuators(or motors). In particular, the folding door mechanism is representative system installed in most of urban buses. To design the folding door mechanism, we construct the kinematic and dynamic analysis model fur computer simulation. Also, the dynamic analysis is accomplished by both direct dynamics and inverse dynamics. Since the folding door mechanism has many design variables, the analysis program is developed to perceive kinematic and dynamic characteristics according to the design variables and simulation conditions.