The wastewater treatment process (WWTP) is difficult to control because it is a time varying nonlinear system.In this paper, an adaptive PID controller based on the RBFNN is applied in the WWTP.The RBFNN can identify the controlled plant online.Then the parameters of the PID controller can be adjusted to adapt to the real-time plant based on the identification.In further study, an optimal rate factor is introduced to improve the adjusting effect The simulation results illustrate that this control strategy has a low integral of the absolute error (IAE), integral of the square error (ISE) and mean square error (MSE).