In order to research the mechanical properties and microstructure change regulation of cement-mixed soil under erosion environment, several experiments are carried out in laboratory. The changes of shear strength of cement-mixed soil are recorded under different erosion environments and in different erosion periods. Their corresponding photomicrographs are also shot to reveal the damage on cement-mixed soil under erosion environment. The results indicate that the shear strength of cement-mixed soil in erosion solutions is worse than the strength by the natural curing in the corresponding period. As erosion time increases the strength of cement-mixed soil dipped in , and solutions keeps on downtrend, whereas the strength of that dipped in unpolluted water and solution presents upward trend. The erosive effects of cement-mixed soil are mainly caused by and , meantime has more prominent erosive effect on cement-mixed soil than . Accompanying with stadium increasing quantitative parameters of microstructures are all varying markedly and have certain regulation which testifies the notable relativity between the shear strength and microstructural parameters. Liner regression methods are set up to indicate the relationship of shear strength indexes and microstructural parameters in the erosion environment.