In this paper, a cable-driven puncturing surgery robot named cable-driven puncturing surgery robot (CPSR) is proposed for soft needle. The cable-driven mechanism has lower mass, smaller dimension and smooth transmission. The motor driving the rotational joints is separated using cable, which strengthens the dynamic performance of the robot. A decoupling mechanism based on movable pulley is also proposed to eliminate the cable coupling error. Transmission error of cable-driven mechanism is also analyzed to improve the control accuracy. The simulation of transmission error is completed to optimize the design parameters of cable-driven mechanism. In experiments, the feasibility of the cable decoupling mechanism is validated. Also the insertion error less than 0.7 mm and repeatability less than 2.5 mm are achieved. Finally the reasons limiting the accuracy and corresponding solutions are discussed. In the future research, the shape sensor will be fabricated using optic fiber and mounted on the slim needle which are helpful to complete automated operations with higher accuracy.