The invention discloses an electronic brake booster which comprises a motor and a servodriving device. The servodriving device is driven by the motor and provided with a rotating/translation conversion transmission mechanism. The electronic brake booster is characterized in that the conversion transmission mechanism comprises a ball screw and a first set of worm and gear matched with the ball screw, the first set of worm and gear comprises a first worm gear and a first worm, the ball screw comprises a screw and a nut, the nut is in coaxial transmission connection with the first worm gear, the nut is driven by the first worm gear to rotate, and the first worm is in transmission connection with the motor. By means of combination of the worm and gear and the ball screw, the rotary driving motion of the motor is converted into translation output motion for controlling a braking system, and the ball screw is adopted for replacing rack transmission, so that the size of a booster body is reduced, transmission noise is lowered, and transmission efficiency is greatly improved. The ball screw achieves flexible transmission, and is not likely to be abraded and long in service life.