An invented patent about the method for separating image of Atom Force/Photon Scanning Tunneling Microscope (AF/PSTM) and its numerical simulation results are introduced. In AF/PSTM π-symmetry lighting beams were used for eliminating false image. The AF/PSTM bi-functional tip is made of bent optical fiber and works on constant amplitude resonance. △I_CD and △I_CI are AC information of photon tunnel of AF/PSTM under constant average distance (〓→A )scanning mode (constant amplitude mode) and constant average intensity scanning mode respectively. Both (△I_CD/〓_CD)² and (△I_CI)² are approximately linear with refractive index (n₁) of the sample. Results of the numerical simulation illustrate that the method for separating image of AF/PSTM is efficient. AF/PSTM constant average distance (〓→A ) scanning mode (constant amplitude mode) has more advantages than that of constant average intensity one, such as the better response sensitivity of refractive index of the sample, and ability of getting three images of transmisitivity, refractive index and morphology of sample simultaneously. Some excellencies of this method are listed at last.