Based on the dynamics theory of rolling bearing,the dynamics model and nonlinear dynamics differential equations of the cylindrical roller bearing during the start up are obtained by considering of the change of lubrication state between rollers and rings. The simulation analysis for the effect of radial loads,accelerations of the inner ring,viscosity of lubricating oil and working temperatures on the slippage characteristics of roller are carried out by solving the equations. The results show,during the start up of the cylindrical roller bearing,the rotational speed growth of the roller about its axis is not linear but stepwise,and there exists a more serious slippage in the early start. The slippage ratio of roller varies heavily with radial loads or accelerations of inner ring. A proper increase in viscosity of lubricating oil or an appropriate decrease in working temperature can reduce the slippage of roller to prevent the raceway scratch effectually during the start up,and effect extent of working temperature is smaller than viscosity of lubricating oil.