By studying on the theory of partial differential equation(PDE), the principle of filtering based on PDE is analyzed, and its correlativity with traditional filter is discussed in theory. From the view of traditional filter design, problems of parameters design are solved, such as evolution time, iterative time, modulation coefficient. Influencing factors of PDE filtering are analyzed. Taking advantage as base difference format, iterative equation is constructed. Experiments show that the method could effectively eliminate the noise disturbing , also avoid signal distortions after denoise, and at the same time keep the edge property and continuity.