Measures as thinˉsection analysis，claym ineral X-ray diffraction，vitrinite reflection and physical proˉperty analysis of oil layer，combined with the results of a regional petroleum geological study，were applied to the research of the relationship between authigenic m inerals and secondary porosity of the deep clastic reservoirs in the3 rd and4 th members of the Paleogene Shahejie Formation in Jiyang Depression.The result shows that，for the3 rd member，the secondary porosity of the depth intervalwithin3150-3600m are related to the dissolution of acid-soluble components such as carbonatem inerals，while thatwithin4250-4500m are formed by dissolution of alkali-soluble components.In contrast，for the4 th member，the secondary porosity of the depth intervalswithin3350-3600，3950-4200and4500-4900m are formedmainly by dissolution of acid-solublem inerals，and those within5600-5700m are connected with dissolution of alkali-soluble components.For the depth interval of4400-4700m in Chezhen sag，the low content of kaolinite and high content of ledikite coincide wellwith high secondary porosity.For the deep layers in northern Dongying sag and Bonan sag，high content of chlorite coincide relativelywellwith high secondary porosity and present amutualwaning and waxing relationship with the ledikite content.For the depth interval of3500-4800m in the Bonan sag，there is an abnormal clay mineral transforming zone，and high I/S ratios coincide relativelywellwith an abrupt increasing of chlorite and high secˉondary porosity.