To reduce the fatigue fracture caused by the friction and wear of a piston ring and ensure the volumetric efficiency and reliability of a motor, the friction of the piston ring was expressed linearly with the normal pressure and shear stress, the modal analysis method and the finite volume method were used to investigate the multi-body dynamics of the system and the fluid dynamics in the cylinder bore respectively, and the normal pressure and wall shear stress of the ring under different spindle angles, different width diameter ratios and arc cone angles were calculated. The results show that the change of displacement caused by the change of spindle angle has little effect on the friction, while the change of structural parameters of sealing ring has obvious effect. When the ratio of width to diameter is less than 0.3 and the angle of arc cone is less than 1.8°, the friction decreases with the ratio of width to diameter and cone angle. When the ratio of width to diameter is 0.3 and the angle of arc cone is 1.8°, the friction reaches the minimum and the maximum reduction rate is 28% and 25%, respectively; however, when the aspect ratio is greater than 0.3 and the arc cone angle is greater than 1.8°, the friction increases the aspect ratio and the cone angle. In addition, the shear stress increases with the ratio of width to diameter, but it is less affected by the cone angle of the arc surface. The research results provide theoretical basis and scientific basis for the design of piston motor piston ring friction reduction strategy.