For the flexible manipulator, rigid-flexible coupling dynamics model was established based on the Lagrangian equations by regarding the flexible joint as a non-linear torsional spring model. Assumed model method was used to transform physical coordinate to modal coordinate. ADAMS was adopted to build virtual prototype for simulation of link flexibility. A Runge-Kutta algorithm was programmed by Matlab to solve dynamics equations considering both link and joint flexibility. Aiming at simulation of manipulators swing under the gravity and driving torque, tip deformation and angle under different loads were given. Coupling characteristics of the joint and link flexibility were studied. Results showed that joint flexibility could not be ignored. The vibration range of manipulator under coupling of the joint and link flexibility was less than sum of individual flexibility vibration. Vibration mode was determined by the joint and link flexibility jointly, but amplitude was mainly influenced by driving torque. The dynamics and solving method were proper.