In the traditional prism surface plasmon resonance (SPR) sensor system,the resonance trough is shallow and the valley is smooth,which causes the resonant wavelength difficult to determine. A novel detecting system is built which added a polarized beam splitter (PBS) based on traditional prism SPR sensor system. In the experiment of alcohol detection,when the S polarized light is filtered,the resonance radius of curvature decreases from 86.2394 to 39.3990,similar to the S polarized light presenced′s 50%,which coincides with the theoretical analysis. Traditional and novel prism SPR sensor system is used to measure 6 kinds of liquid whose refractive index is 1.32-1.39. The resolution ranges from 1.62×10－4 to 1.55×10－4. The detecting system with filter S polarized light that doesn′t excite SPR effect,which making a more acute resonance trough,thus detecting system has been improved.