The conventional petroleum field in Jiyang Depression has always been the main battlefield of exploration and development in Shengli Oilfield. It has experienced more than 60 years of exploration and development and entered the mature exploration stage as a whole，but it still has a relatively large scale of reserve increase every year，which is not consistent with the traditional growth trend of proven petroleum-in-place in oil and gas-bearing basins. The critical issues concerning the exploration decisions of Shengli Oilfield need to be clarified urgently，including the growth law of the conventional proven petroleum-in-place in Jiyang Depression，the strong trend of reserve increase，and the main fields for reserve increase. By analyzing the exploration process of Jiyang Depression，the geological characteristics，resource conditions， exploration investment， theory and technology，resource sequence，and other exploration elements were analyzed，revealing the exploration discovery law of conventional petroleum in Jiyang Depression. The broom-shaped model prediction method and proven rate method of resource were used to predict the growth trend of conventional proven petroleum-in-place. The scale and favorable direction of future reserve increase of conventional petroleum in Jiyang Depression were clarified by analyzing the main fields with reserve increase. The results show that the complex geological characteristics of Jiyang Depression and the relatively abundant remaining resources determine the diversity of exploration objects，the tortuosity of the exploration process， and the long-term nature of exploration history. The conventional petroleum in Jiyang Depression can still maintain a long period of stable reserve increase under conditions of ensuring a relatively stable exploration investment，continuing to innovate the exploration theory and key technologies， and maintaining a relatively reasonable resource sequence.Jiyang Depression can still produce about 2.5 × 10⁸t of conventional proven petroleum-in-place in the next 10 years under the current economic and technical conditions and the relative guarantee of exploration investment. It is pointed out that the Neogene river sandstone reservoir， lithologic oil and gas reservoirs in the Upper Submember of the 4^th Member of the Eocene Shahejie Formation（Es₄^U）-the Lower 3rd Member of the Eocene Shahejie Formation（Es₄^L）， and other mature fields are still the ballast stones for stable reserve increase. Kongdian Formation-the deep field of the Lower Submember of the 4^th Member of the Eocene Shahejie Formation（Es₄^L） is an essential field for large-scale reserve increase，and the pre-Paleogene buried hill is a favorable direction for the petroleum enrichment and high yield. In the future， the exploration progress in the unconventional and new energy fields should be closely tracked， and the research results of the growth law and the reserve increase trend of conventional proven petroleum-in-place in Jiyang Depression should be constantly improved and revised to make them more conform to the development trend of oilfield exploration and guide the oilfield exploration decisions.