Abstract: With the basis of petrological and mineralogical studies on the algal-dolomitic coressampled from the different depths of the upper 4th Member of the Shahejie Fr.(E₂) and apart of the paleozoic system,it is suggested that the change of proto-dolomite into ideadolomie should occur along with the increasing temperatures throtigh the calcium excretion-and the adjustment of inner crystal lattices.By such an evolution,the inter-pores developed in dolomitic formations and consequently,the evolutionary models can be establishedfor the algal-dolomite diagenesis.