Abstract: A flexible parallel mechanism with 6-DOF driven by 9 cables is presented. The structure matrix of the cable driven parallel mechanism is deduced by a statics equation. Using the force-closure method, the force distribution is calculated. Based on the force of each cable in different positions, feasible workspace is achieved under the specific design parameters and the specific force conditions. The optimization design of the cable driven parallel mechanism is carried out based on the workspace and the workspace distribution. Some typical design parameters, including the positions where the cables are fixed on the base frame and the positions where the cables are connected on the moving platform, are investigated in detail based on 3 different experimental design methods, which is used to select valuable sample points, and response surface method, which aims at building second order polynomial regression mode to obtain desired optimization results. Moreover, the virtual prototype experiment based on the ADAMS is utilized to verify the accuracy of the optimized results and the resonability of the optimization progress.