In view of the deterioration of the lubrication performance of the main bearing of a diesel engine after power boosting,by taking the surface profile and elastic deformation into account,the lubrication analysis model of the main bearing of 12V150 diesel engine was established.Based on elastohydrodynamic lubrication(EHD),bearing dynamic and GreenwoodTripp asperity contact theory,the lubrication performance of the main bearing after power boosting was analyzed and the parameters that need to be improved are proposed.It is found that the main reason for the poor lubrication performance of the main bearing is that after the power of the diesel engine is increased,the load on the crankshaft and the main bearing is intensified,and the oil film pressure is increased,which causes the journal to bend or tilt and results in the decrease of minimum oil film thickness of the main shaft.The influences of crankshaft balance rate,bearing width and lubricating oil viscosity on bearing lubrication performance were studied,an improved scheme is put forward to increase the crankshaft balance ratio from 70% to 90%,the bearing width from 46 mm to 48 mm,and increase the lubricating oil viscosity reasonably.The results show that the crankshaft balance rate can effectively reduce the journal misalignment,while the bearing width and lubricating oil have little effect on the journal misalignment.After the structural improvement,the minimum oil film thickness of the bearing is increased by 16.08%,the peak contact pressure is decreased by 37.11%,and the average friction loss power is decreased by 13.08%.