Aiming at the control problems of air-cushioned headbox in papermaking process，such as the nonlinearity and serious coupling relationship between total pressure and liquid level，a double variable PID decoupling controller based on BP neural network is proposed to release the influence between the two variables.The controller changes the parameters：proportion（kp），integral（ki），and differential coefficient（kd）of PID itself on line with neural network’s capability of non-linear description，in order to find the best PID parameters，which can release the influence between total pressure and liquid level of the air-cushioned headbox.The results of simulation on air-cushioned headbox’s linear and non-linear model indicate that the controller has the characteristics of simple realization，quick dynamic behavior，high control effect and better practical value.