Aim at processes with large time delay in actual industry, a self-adjusting method on filter time constant is proposed based on internal model control (IMC) method. Meanwhile, A fuzzy self-adjusting rule of filter time constant based on IMC method is presented. Simulation results show that this method is not only effective for the dynamics and the stability of control system but also effective for process robustness. In addition, the method can provide good performance when model matches actual process perfectly, and better response when model mismatches actual process. It is prone to engineering application.