The statics and stiffness model of serial-parallel manipulators (S-PMs) formed by k parallel manipulators (PMs) connected in series is established in this paper. The S-PMs can provide features of both serial manipulators (SMs) and PMs. First, the unified formulae for solving the statics and stiffness of S-PMs are derived. Second, a k(PS + RPS + SPS) S-PM is analyzed to illustrate this model. Finally, an analytic solved example for 5(PS + RPS + SPS) S-PM is given. The established model can offer an essential theoretical basis for S-PMs.