Abstract: In order to improve the large travel stiffness in direction Z and the comprehensive performance of the hybrid robot,a five degree-of-freedom（ DOF） hybrid robot 3-RHUR/PUS + PP was proposed,which was composed of a 3-DOF parallel head with a following sliding barrel in series double slideways.Firstly,the forward and inverse position solutions were given based on the nonlinear constrained equations. Considering the parallel mechanism and the series mechanism,the forward and inverse kinematics mapping relationships of the hybrid robot were established based on the screw theory,which provided the basis for the research on the overall performance of hybrid robots. The stiffness of the direction without DOF was infinity,because the hybrid robot was lower-mobility hybrid mechanism. Its direction stiffness was discussed by the flexibility model of the hybrid robot. Secondly,taking into account the rotational ability, force transmission performance, speed performance and stiffness performance of the 3-RHUR/PUS + PP hybrid robot,the hybrid robot was optimized with multiple objectives on the basis of the linear weighted method. The optimization algorithm combining optimal Latin hypercube sampling（ OptLHS） and interpolation was proposed,which shortened the time required to optimize the calculation and obtainedthe optimal parameters of the robot. Finally,according to the optimization result,the preferred robot parameters were obtained,and its rotational ability,speed performance and stiffness performance were studied.