Abstract: In this paper,the Lower Tertiary algal dolomite and the Ordovician dolomite are taken as sampling material and secondary distilled water as a medium.The preliminary results of diagenesis modelling experiments under different temperature(100～200℃),pressure(100×10⁵～300×10⁵Pa)and time(7～21 days)showed that dolomite itself has internal causes of changing into ideal dolomite with the rising of temperature in the ways of calcium-discharge action and internal lattic adjustment.The outcome of this progress is that pores emerge with the volume reduction of mineral itself.