Under the axial excitation of the propeller,the axial movement of the crankshaft on the large marine diesel engine is obvious.In order to explore the effect of the axial movement on the lubrication of the main bearing supporting the crankshaft,a crankshaft-bearings system of a marine diesel engine was taken as the research object,and a mixed-lubrication model of marine diesel engine main bearing was established by considering the axial motion caused by propeller axial excitation and diesel engine self-excitation and the asperity contact (dry friction) .The axial movement of the crankshaft was obtained by using finite element method.Combined with the dynamic method,the oil film pressure was obtained by solving the average Reynolds equation considering axial motion and surface roughness,and the asperity contact pressure was obtained based on the Greenwood-Tripp contact model.The results show that after taking into account the axial motion,the oil film peak pressure and oil film frictional power loss of the bearings are reduced,and the asperity contact pressure is increased.However,the asperity contact frictional power loss of some bearings increase and the others decrease among the 8 bearings.The influence of the axial motion on the asperity contact is significant,but the reasons are complicated.After taking into account the axial motion,the minimum oil film thickness,end leakage of bearing,journal center orbital path change little.Thus,the axil motion of the crankshaft must be considered to predict the mixed-lubrication of main bearings of the large marine diesel engine more comprehensively and more accurately.