With the increase of mining output of shallow and middle oil and gas resources， oil and gas resources exploitation gradually extends to deep and ultra deep layers. With the increase of depth， for conventional screw motors， it is impossible to solve the problem of high temperature failure of rubber bushings of its components. Therefore， designing an all metal screw motor is of great significance. This article selects the 7LZ178 all metal screw motor and analyzes its impact on the performance output of the motor from two aspects： the linear design of the stator and rotor end faces of the screw motor and the clearance ratio of the stator and rotor of the all metal screw motor. This article starts with the end face shape of the screw motor and compares and analyzes the formation principles of four types of shape， as well as the advantages and disadvantages of the four types of shape. A three-dimensional model was established using a common internal swing type stator and rotor line shape for fluid simulation. The changes in output parameters such as pressure and torque of the screw motor with changes in stator and rotor clearances were briefly analyzed. Exploring the pressure drop variation trend of metal screw motors under different clearance values provides reference significance for determining the optimal range of clearance fit of screw motors under corresponding design parameters.