In order to investigate the influence of impurity particles mixed in oil on the lubrication performance of needle roller bearings,a line contact lubrication model considering individual impurity particles was established based on the lubrication model of line contact needle roller bearings.The multi grid method was used to calculate the oil film pressure,the multi grid integration method was used to calculate the elastic deformation of the oil film,and the column by column scanning method was used to calculate the oil film temperature.The oil film pressure,film thickness,flow velocity,and temperature changes of particles flowing in the contact area under different entrainment speeds,loads,and particle sizes were obtained.The results indicate that the presence of solid particles can cause an increase in oil film pressure and temperature near this location,a decrease in film thickness,and fluctuations in fluid flow rate.A decrease in the suction speed,an increase in load,and an increase in the size of impurity particles will significantly increase the pressure and temperature at the location of the particles in the contact area,leading to adverse working conditions and causing adhesion or pitting between the roller needle and the raceway at that location.