Different types of anomalously high porosity zones have different genetic mechanisms and require different exploration phi- losophy. According to relative content of primary pores versus secondary pores in reservoirs, anomalously high porosity zones can be divided into primary anomalously high porosity zone with content of primary pores more than 50% and secondary anomalously high porosity zone with content of secondary pores more than 50%. Though all the anomalously high porosity zones in Paleogene reser- voirs in the northern steep slope zone of the Dongying sag are currently defined only as secondary porosity developed zones, there widely exist geological factors,which favour preservation of primary pores, such as fluid overpressure and enormous hydrocarbon fill- ing. Therefore, a systematic study was carried out on clastie reservoirs in the Member 4 and the middle Member 3 of the Shahejie Formation in the northern steep slope zone of the Dongying sag. The results show that two anomalously high porosity zones develop at 2 800-3 300 m and 3 300-3 700 m, respectively, in the Shengtuo area and content of primary pores is from 50 % to 90 %, indicating a primary anomalously high porosity zone. In addition, two anomalously high porosity zones develop at 4 250 -4 400 m and 4 750 4 900 m, respectively, in the Minfeng area and content of secondary pores is from 60% to 90%, suggesting a secondary anomalously high porosity zone.