The discovery of Bozhong 19- 6 gas field, the largest integrated condensate gas field in eastern China in 2018, has opened up a new field of deep gas exploration in the Bohai Bay basin, showing great potential for gas exploration in oil- type basins with multiple sets of source rocks with different maturity and various chemical features. Condensate and natural gas co- exist in Bozhong 19- 6 gas field located in the southwest of Bozhong Sag. The formation mechanism of condensate gas has been seriously debated for long time; however, no study has integrated it with genetic types of condensate oil. Taking the Bozhong 19- 6 condensate gas as an example, this study employs geological and geochemical methods to determine the formation mechanism of condensates oil and condensates gas in a complicated petroliferous area, and reveals the causes of the co- occurrence of condensates gas and oil in this region. Based on detailed geochemical analyses of 6 condensates oils, it is found that the condensates are dominated by low carbon number n- alkanes and enriched in light naphthenics and aromatic hydrocarbons. Adamantanes are present in abundance, with low abundance of high carbon biomarkers. It is concluded that condensate oils belong to mixed high mature crude oil. Combined with the comparison results of condensate oils and natural gas in this area, it is concluded that the condensate oils and natural gas belong to the same set of hydrocarbon compounds generated by the same source rock at the same stage, and they are both the products of the source rock.