An automatic safety nail clipper, comprising a disc-shaped blade (5), a blade driving device and a clipper cover (4). The blade driving device is connected to the disc-shaped blade (5), nail inserting ports (1) are arranged on the clipper cover (4), the nail inserting ports (1) correspond to the disc-shaped blade (5), several nail inserting ports (1) are arranged on the circumference of the clipper cover (4), and the sizes of the nail inserting ports (1) are different from each other, and protruding arc-shaped sheets (2) are arranged at the nail inserting ports (1). According to the automatic safety nail clipper, since the plurality of nail inserting ports (1) are provided, a proper nail inserting port (1) can be selected according to the size of a finger to be trimmed. Meanwhile, the protruding arc-shaped sheets (2) being arranged at the nail inserting ports (1), muscles of the fingers can be obstructed from the nail inserting ports (1) for avoiding hurting the fingers during trimming.