Abstract: Based on test results including physical and mechanical properties, analyses of X ray diffraction and scanning electron microscope for dark soil,cement stabilized dark soil and their in situ core sample,this paper analyzes not only the variation of the unconfined compression strength and modulus with cement mixing ratio and curing time, but also the relation between strength obtained by laboratory and in situ tests. Besides, the evolution mechanism of strength for cement stabilized dark soil is described in this paper. Finally, suggestion of cement mixing ratio for cement stabilized dark soil in DJM pile is proposed.