The utility model discloses a feeding device of wire saw which comprises a bracket, a lead screw, a motor, one or more guide rails and a saw bow plate frame; wherein the lead screw are in rotary connection with the bracket, the motor is arranged on the top of the bracket with the output shaft connected with the lead screw, the guide rail is arranged on the bracket and the saw bow plate frame is arranged on the guide rail to slip and is connected with the lead screw by a worm gear. The feeding mechanism of the utility model can realize the step-less speed regulation and can indirectly adjust the tensile force of the beaded rope. So, the feeding mechanism can better maintain the stability of the tensile force during the process of cutting.