Abstract: Based on the examinations of rock sections, scanning electronic microscope and casting sections,and porosity and permeability of rocks,the author studied the diagenesis and reservoir properties in details. Diagenesis involves processes as follows. 1.transformation 2.replacement 3.compaction and pressolution 4.biological activity 5.cementation, 6.solution, 7.recry-stallization, as a combination of which diagenetical fractures and structural fractures developed. Notice should be paid to semi-filled-unfilled shells and horizontal fractures between cements. Interstitial pores, inter-stitial pores and solution pores within shells, and solution pores formed in late diagenesis stage, and microfractures resulted from pressolution which were eventually collaborated with diagenesis fractures, diagenetic solution fractures, structural fractures could improve reservoir properties. It is thought Daanzhai Menber is composed of reservoir of pore-fracture type, and suggestions for oil and gas exploration are provided.