A 2(SP+SPR+SPU) manipulator is a serial-parallel manipulator, which includes an upper manipulator and a lower manipulator. Its stiffness and elastic deformation are studied systematically in this paper. Firstly, a 2(SP+SPR+SPU) manipulator is constructed and its characteristics are analyzed. Secondly, the formulae for solving the elastic deformation and the compliance matrix of the active legs are derived and the elastic deformation and the total stiffness matrix of this manipulator are solved and analyzed. Finally, a finite element model of this manipulator is constructed and its elastic deformations are solved. The analytic solutions of elastic deformations of this manipulator are coincident with that of its finite element model.