Non⁃metallic pipes are widely used in the gathering process and oil pipeline due to their excellent performance，but the calculation of the friction coefficient is still in the exploration stage. In this paper，the effects of the surface roughness and wettability of the inner wall surface of the oil pipeline on the frictional resistance of the fluid in the process are summarized，and the surface slip effect caused by the change of surface wettability is introduced. The wettability of the inner wall surface of the liquid and the pipe and the influence mechanism of the boundary slip effect on the friction coefficient along the path are discussed. The results show that the friction coefficient is affected by the roughness of the inner surface, the wettability of the fluid and the inner surface, the surface slip effect caused by the wettability and the surface tension of the liquid.