Abstract: According to the study of pores of deep elastic reservoir in Shahejie Formation of Qikou Depression, there are 7 pore types and 4 pore throat types. The textural characteristics and development characteristics of secondary pores were described particularly. The formation mechanism of secondary pores was analyzed systemically. It was ensured that the forming causes of secondary pores were organic cause and the inorganic Cause was subordinate, and the former is the main cause while the latter is subordinate and the two causes reacted together. The geologic factors which influenced the development of secondary pores were discussed, and the reservior was evaluated based on the pore texture and other factors.