In order to solve the problems of low tracking accuracy, large oscillation and poor real-time performance of ball and plate system, a sliding mode control scheme of combinatorial reaching law based on genetic algorithm is proposed. Firstly, the sliding mode surface designed by Ackermann formula is used to express the discontinuous hyperplane; secondly, the exponential reaching law is used to reduce the buffeting amplitude in the early stage of the sliding mode, and the variable speed reaching law is used to converge the buffeting in the later stage. Finally, the genetic algorithm is used to select the parameters. the experimental results show that the initial output amplitude of the combined reaching law is reduced by 2. 2 compared with the variable speed reaching law, and the convergence time after genetic algorithm optimization is reduced by 0. 4 s. The stability of the controller is proved by Lyapunov theory, and the simulation results show that the control strategy has good dynamic quality and steady-state performance, and meets the trajectory tracking requirements of the ball and plate system.