In this paper, the influence of the thermal effect on the lubrication performance of engine main bearing with rough surface considering the axial motion of crankshaft is investigated. In the analysis, the crankshaft-bearing system of a four-cylinder four-stroke engine is taken as the object. The axial motion of crankshaft is measured by the engine bench test. The journal load of main bearing and crankshaft deformation are calculated by the whole crankshaft finite-element method. The analysis model is established based on the average flow lubrication model. The lubrication of main bearing is analyzed by the dynamic method. The temperatures of lubricating oil and bearing are calculated by the energy equation and solid heat conduction equation. The results show that the influence degree of the axial motion of crankshaft on the lubrication of engine main bearing with rough surface is greatly affected by the thermal effect. When the thermal effect is considered, the influence of the axial motion of crankshaft on the lubrication of engine main bearing makes its working condition deteriorate further. When the axial motion of crankshaft is considered, the influence of the thermal effect on the lubrication of different main bearings varies significantly.