The measurement of particle size distribution and refractive index of the thin layers in two-layer tissue phantoms by using the diffuse backscattering light dependent on the azimuth angle of the linearly polarized incident light. In the two-layer model, the upper layer consists of polystyrene pheres suspension or HeLa cells, and the bottom layer is intralipid solution. Optical properties of both layers are supposed to match those of biological tissue. Based on Mie theory, the theoretical model for dependence of particle morphological parameters related polarized diffuse backscattering light intensity on the polarization angle of the incident light is built up. The particle size distribution and relative refractive index are derived by using inverse program of floating genetic algorithm. Comparison of theoretical and experimental results are made, and it is found that the morphological structure information of thin layer tissue can be drawn by measuring and analyzing the polarized differential signal of the azimuth angle-dependent diffuse backscattering light.