The parameters of the controlled object will change when the frequency conversion constant pressure water supply control system is working. Most of the traditional control methods are controlled by PID, but the control effect is poor. In order to water pressure of the water supply system in the building of effective control, the fuzzy adaptive PID controller to adjust the PID parameters automatically according to the pressure deviation and deviation change rate of building water supply network, and through MATLAB simulation. The results show that the fuzzy adaptive PID has better steadystate accuracy and dynamic response compared with the PID, and can meet the control requirements of building variable frequency constant pressure water supply system.