Abstract： The contact phenomenon in flexible multi-body system is common in engineering, which always make great effects to system design and analysis. The contact condition is analyzed and then the contact model of flexible bodies is established using nonlinear spring model as well as the tangential friction is considered by Coulomb friction model. Then the contact model was associated with the equation of flexible multi-body system. So the flexible multi-body system dynamics model is established including contact model, which is applied to common contact multi-body system. The dynamic simulation of contact process of a flexible beam in gravitational field is made to proof the validity and correctness of the model. The dynamic response and the rule of the contact force are discussed in detail, which includes the angular displacement and angular velocity, the time course of contact force and the rule of terminal displacement and velocity. Finally the differences between flexible and rigid beam are compared and discussed in detail. The results show that the nonlinear spring model is availability for contact dynamics of flexible multi-body system.