Abstract: Aiming at the problems of low efficiency and high consumption of bits and drilling tools in drilling hard rock with conventional single bend screw motor, an impact screw motor is developed by adding an impact mechanism between the universal shaft of a common screw motor and the drill bit. The impact screw motor has dual functions of impact and orientation. The structure and the working principle of impact mechanism, the design of key components and the characteristics of the impact screw motor are introduced. Laboratory tests were carried out on the φ89 mm impact mechanism, and the peak impact force was measured to be 5 000-9 000 N, which was in agreement with the theoretical calculation results. The wear resistance of the hammer and anvil of the composite structure composed of cemented carbide and bearing steel meets the requirements of industrial application. Field industrial tests have been carried out in Sihe coal mine of Jincheng Coal Group,drilling efficiency is 20%-30% higher than that of conventional single bend screw motor.