The Southeast Xiang depression, in which the Paleo～Mesozoic strata are generally exposed, is one of the Paleo～Cenozoic superimposed basins in South China. The attention is rarely paid to this area ever before. In this paper, based on the field outcrop survey and the thin section analysis, the major diagenetic types including micritization, cementation, pressure solution, dolomitization, recrystallization, cataclasis and dissolution are analyzed, all the diagenesis took place on seafloor, nonmarine(fresh water and mixed water), shallow burial, deep burial to epigenetic environments. Of all the types of dianenesis, cataclasis, pressure solution, denudation and dolomaitization play a positive role in the porous development of reservoirs. Especially, cataclasis and pressure solution which are very typical in the area, improve the ability of the reservoir rocks, and the dolomite intercrystal pores caused by dolomitization is a very important pore space, in which the favorable petroleum exploration targets are expectable.
