Abstract: A self-tapping screw includes a head, a shank provided on the head and threads provided on the shank, wherein the threads include a first contact surface and a second contact surface forming a thread angle of 40 degrees therebetween. A vertical line from a vertex of the thread angle is drawn perpendicular to the shank, and the first contact surface forms a first inclination angle with the vertical line, and the second contact surface forms a second inclination angle with the vertical line, wherein the first inclination angle is different from the second inclination angle. The present invention can be used to replace mechanical screws as it has a smaller assembly torque suitable for fastening onto lighter objects.