The invention discloses a steering system, an automobile and a steering assisting power adjusting method. The steering system comprises a mechanical steering system, a steering assisting power system and an active steering assisting power adjuster, wherein a driver can operate the active steering assisting power adjuster to increase or decrease the torque output level K, so that correction is conducted on the initial torque output size N by an electronic control unit, and thus the torque output size N after being actively adjusted is obtained; according to the torque output size N after being actively adjusted, an electric assisting power mechanism is operated to provide steering assisting power. According to the steering system, the steering assisting power of the same automobile can be actively adjusted, so that the automobile can meet different requirements of different clients for the steering assisting power.