A novel 3RPS-3SPR serial-parallel manipulator (S-PM) with 6 degree of freedoms (DOFs) is proposed in this paper. It includes a lower 3RPS parallel manipulator (PM) and an upper 3SPR PM. Its inverse kinematics, active forces and workspace are solved. First, the inverse displacement is solved in close form based on the geometrical and the dimensional constraints of this S-PM. Second, the 9×9 and 6×6 form inverse Jacobian matrices are derived and the active forces are solved using principle of virtual work. Third, the workspace of this S-PM is constructed by using CAD variation geometry approach.