Compared with a rigid-link parallel robot, a cable-driven parallel robot (CDPR) has the advantages of a simple and lightweight structure, large working space, fast response speed, and low cost, which is very suitable for extreme space environments. However, due to the complex coupling relationship between the motor, the cable, and the end effector, the solution of the CDPR workspace and stiffness is challenging. In this paper, a modeling, analysis, and optimization method of workspace and stiffness of 4-cable-driven parallel robots is proposed, which is used to guide the design decision of CDPR dynamic anchor position. Firstly, the CDPR kinematics model considering the pulley model is established, and the multi-layer kinematics is solved using the optimization method. Then, the workspace of the CDPR is established, and the solution method of workspace optimization is given. Furthermore, the stiffness model of the CDPR is derived, and the solution method of stiffness optimization is given. Finally, according to the optimized workspace and stiffness model, the anchor position design decision of the moving platform of the CDPR is optimized. The numerical simulation results and experiments verify the correctness and effectiveness of the proposed method.