The circular ball type electric booster steering device has, except screw, nut, gear sector, steel ball and other mechanical parts, torque sensor, boosting motor, decelerating mechanism, electronic controller unit, etc. The electronic controller unit determines the target current of the motor based on the steering disc torque and the vehicle speed to complete the feedback tracking control of the motor current. The decelerating mechanism has input connected to the motor and output connected to the screw or gear sector shaft in the circular ball steering unit. The present invention has saving in energy, provides proper power force fitting different running conditions, and has less parts, light weight, compact structure and high automation.