The invention discloses a semi-automatic double-acting tooth dividing machine, which comprises a motor, a gear transmission system, a double-acting punch press sliding block mechanism, a cam transmission mechanism, a propulsion mechanism and a feeding device, wherein the gear transmission system is connected with an output shaft of the motor, double-acting punch press sliding blocks and the cam transmission mechanism are connected with the gear transmission system respectively, one end of the propulsion mechanism is connected with the cam transmission mechanism, and the feeding device is arranged at the other end of the propulsion mechanism. The tooth dividing machine has the advantages: 1. the tooth dividing machine has high work efficiency, ensures that one person can synchronously operate a few machines, and is suitable for mass production; 2. the tooth dividing machine has good tooth dividing effect and can divide each tooth; and 3. the tooth dividing machine has high tooth dividing quality and can divide teeth symmetrically in the left and right sides.