Abstract It's the foudation of error control that nonlinear dynamical analysing for rigid-flexible coupling manipulator.The system of astronautics manipulator is equivalent to a RRRP system including an infegrated mass. The one order similar modal function of extendible manipulator is set up by use of finite element method. It’s dynamic model is set up by use of Lagrange’s Equation and the assumed mode method. With help of Longgekuta numerical method, the dynamical characteristic of the rigid-flexible coupling RRRP system are found. The numerical results indicate that the change of the structure parameters will influence the lateral vibration of the manipulator. Based on the above results, its optional design and error control can be realized.