The barrel heating system of injection molding machines is dealt with in this paper. To solve the problem of strong coupling operation of adjacent heating zones in this MIMO system (for example, 4 input and 4 output variables), the authors introduce a method which is simple, direct and easy to realize. By adopting this method, a single channel decoupling control can be gained simply bud on the value of the input and output variable of each channel. The experimental results show that the algorithm is of great engineeing value and broad applicahon in the future.