Abstract: Conventional comparative test, rheological property comparative test, permeability comparative test, hydration heat analysis and micro-structure analysis on oil well cement with and without micrite was carried out in lab. This paper presented that micrite mechanism was the solid reaction mechanism of heterogeneous nuclear and its reaction rate was determined by diffusion velocity during the hydration of cement. The micritic cement had the characteristics of low cost and high performance. The gas permeability of micritic cement stone was lower than 1(10-3(m2, its compressive strength of cement can be 70MPa at the most. The test showed that micrite can hardly have effect on the per formance of cement and it can only have action on the formation and development of cement stone.