Aiming at the problem that the overshoot of the traditional optimization algorithm in the optimization of PID parameters is too large due to the improper selection of objective function, which results in the slow reaction speed and poor stability of the system, a new method based on the traditional genetic algorithm and introducing penalty function is proposed to construct a new one according to the overshoot in the system. The objective function is used to optimize the parameters of PID. Experiments show that this method can effectively reduce the overshoot in the system, speed up the optimization and operation speed while ensuring the stability of the system, and realize the optimization of PID parameters.