An ultrasonic therapy system capable of reducing the electromagnetic interference to the imaging device includes an imaging device, an ultrasonic therapy device and an electric controlling unit. The ultrasonic therapy device includes an ultrasonic therapy applicator and the movement positioning units thereof. Driving motors for controlling the movement of the ultrasonic therapy applicator are provided in the movement positioning units, wherein the driving motors are disposed outside the area where the electromagnetic wave of the driving motors can interfere with the imaging device, and the driving motors are connected to the ultrasonic therapy applicator through gearing units.