The invention relates to a mold locking device comprising an upper mold installation plate, an upper mold and a lower mold. The upper mold is arranged on the bottom face of the upper mold installation plate. The edge of the top end of the lower mold is provided with a flange. The outer side of the lower mold is provided with multiple installation platforms. The installation platforms are fixedly connected with the lower mold. The installation plates are arranged on the upper surfaces of the installation platforms. The portion, close to the lower mold, of each installation plate is provided with a motor. An output shaft of each motor is connected with a lead screw. The lead screws are provided with locking rods which are connected with the lead screws in a threaded manner. The outer side face of the flange is provided with locking holes corresponding to the locking rods. The outer side face of the upper mold installation plate is provided with locating holes corresponding to the locking holes. The mold locking device is simple in structure and good in mold locking effect.