The research object is the bridging mechanism of mobile treadway bridge. A novel spreading and erection scheme of the bridge was proposed and the kinematic and dynamics analysis of the bridging mechanism were studied. By using analysis software ADAMS, a parameterized model was established and the bridging procedure of single/double modular bridge bay was simulated. On the basis of previous work, the design of experiment was carried out and the key design variables which produce a huge effect on the mechanism were chosen and verified by selecting the limit load of key rods (hydraulic cylinder) as study object. The method can reduce the work amount and improve the design efficiency a lot under the condition of design requirements. It can also provide a reference to the optimization of this kind of bridging mechanism.