Connecting rod small end bearing is the key friction pair in internal combustion engines.It is prone to deformation and seizure failure under low speed and heavy load conditions,which is an important reason affecting the reliability of heavy-duty truck engines.To reveal the performance of connecting rod small end bearings under low speed and heavy load conditions,the tribological dynamic model of piston-connecting rod-crankshaft was established to analyze the connecting rod small end bearing of a 6-cylinder diesel engine.The torque of the connecting rod small end bearing and the piston pin hole bearing on the piston pin was considered in the model.Then the transient elastic deformation of the small end bearing was coupled into the model,and the influence of bearing deformation on the tribological performance prediction results was analyzed.The results show that under the low speed and heavy load conditions,ignoring the bearing deformation may make the predicted rotation direction of the piston pin opposite.During the suction stroke,the small end bearing is severely deformed and resulting in lubrication deterioration between the bearing and the piston pin.