In fluorescence microscope, the weak fluorescence signals are usually submerged in the strong excitation light. The fluorescence microscope image quality seriously depends on the ability to extract the faint fluorescence signal from the strong excitation light. At present, the image enhancement using frequency filtering to filter out the excitation light, is often used in the fluorescence microscope, based on the differences between fluorescence and excitation wavelength. However, while this method is used, the parameters of the filter will be required highly, and seriously depend on the wavelength of the fluorescence and the excitation light. A polarization filtering image enhancement technology to filter out the excitation light and enhance image quality, is proposed, based on the differences of the polarization characteristic between the fluorescence and the excitation light. The experimental results indicate that when the filtering method is utilized, the image quality is improved significantly, and the requirements of the optical components performance parameters, is significantly reduced. The study is not only to enrich the technological method to extract the weak fluorescence signal from the strong excitation light, but also a reference for developing a light wavelength tunable multi-spectral fluorescence microscope.