Abstract: In order to solve the problem of the calculation method about the rolling friction arm of a hydraulic steel gate roller, the contact problem between wheel and rail is reduced to the contact between the cylinder and the cylinder seat. Taking the contact line as the end of the semicircle, it assumes that the pressure of the contact line is proportional to the height at the point of this semicircle.The analytical solution of a rolling friction arm is derived according to the Boussinesq problem of an infinite half-plane solution. Finally, ANSYS is applied to computing the contact between rolling wheel and rail to verify the correctness of the analytical solution of the rolling friction arm. The results show that the rolling friction arm formula is reasonably simplified, and the calculation accuracy can meet the actual requirements.