An automatic torque regulating system includes a base, a plurality of positioning rods mounted on the base, a first disk mounted on the positioning rods, a second disk moved with the first disk, a hollow bushing sandwiched between the first disk and the second disk and pivotally connected a force input shaft and a force output shaft, a plurality of cams moved in concert with the first disk and the second disk and pressing a conic face of the force output shaft. Thus, when the first disk and the second disk are moved, the cams are moved axially relative to the force output shaft to change different contact points between the cams and the conic face of the force output shaft so as to regulate the torque automatically.