Abstract  Based on the analyses of over 310 sandstone samples from 53 well, the Taizhou Formation reservoir in the Subei Basin experienced burial (pressolution) , cementation and dissolution process, while the diagenesis showed different characteristics at different locations. The Haian Sag located in eastern part of Subei Basin is dominated by cementation and dissolution, with nonobvious burial and pressolution. The burial extent in the Gaoyou Sag is stronger than that in the Haian Sag. The reservoir porosity of the Taizhou Formation in Gaoyou Sag was about 10% at depth of 2400～2800 m, while was about 10% ～20% in Haian Sag. Currently, the Taizhou Formation in the Haian Sag and Gaoyou Sag is at the age A of mid-diagenetic stage. The reservoir quality is mainly controlled by comprehensive influence of the initial sedimentary environment and diagenesis. Burial and cementation both can reduce the pore space, but when the carbonate cements content is lower than 15%, ementation has smaller influence on the reservoir quality. The carbonate cements and feldspar grains created a great deal of intergranular pores. The favorable reservoir in the Haian Sag in mainly distributed in the northwestern and eastern delta front sandbodies and turbidity fan sandbodies, while in the Gaoyou Sag, it is distributed in southern fan delta front sadnbodies.