To reduce the shock and oscillation of the wafer stage of lithography during step and scan movement,an algorithm of S-curve trajectory was researched in this paper.The compound method of the S-curve trajectory planning method which introduced adjustable weighting factors to consider both time and shock factors were used to research the step movement,acceleration of scan movement,and deceleration of scan movement.Based on the simulation of step and scan movement,a simulation of "step +scan"was conducted for a specific distribution exposure field.The simulation results showed that compared with the conventional 3rd order trajectory planning,the aceleration profile of the researched S-curve trajectory was smoother and less likely to excite residual vibration in the flexible link,which could effectively reduce shocks and oscillations and ensure the stability of wafer stage of lithography during scanning.