Water supply pumping station is a variable frequency and constant pressure system to ensure water pressure stability, which can respond quickly and stably under the disturbance. In order to improve the stability and efficiency, this article proposes an improved PSOBPNN adaptive PID control method. Firstly, the variable frequency and constant pressure control model of water supply pump station is established. Then, PSO weight iterative strategy based on BPNN is proposed to improve optimization efficiency of PID parameters, so as to preferably satisfy the control requirements. The results show that the proposed algorithm responds quickly without overshoot, and shows stable tracking capability for nonlinear signal. Compared with the PID control algorithms of BPNN and PSOBPNN, the proposed algorithm can shorten the regulation time by 296% and 28% in the constant voltage experiment, and the overshoot is reduced by 346% and 199%, and the stabilization time is shortened by 73% and 16% in the disturbance experiment. The algorithm can improve the stability and efficiency of water supply pumping station system.