Considering the viscoelastic properties of belt and combining finite element method and mutibody dynamics theory,a new discrete model of belt using rigid elements describing the rigid property and spring-damping elements describing the flexible property is brought out. Based on Lagrange equations of the second kind,the dynamics differential equations of rigid elements are established. Then,the flexible multibody dynamics equations of belt conveyor system are established by using recursive synthesis method. The running speed of a belt conveyor in starting phase is simulated by this modeling method. The correctness of the simulation results and the practicability of the method are validated by the field testing results of a belt conveyor. The simulation results provides not only the basic data for dynamic design but also valuable theoretical basis for further research on belt conveyor.