Doseo basin, one of the key CNPC overseas petroleum exploration blocks, located in the rift systems of Central Africa, is in the stage of low- degree exploration. Based on systematic organic geochemical analysis of 131 shale cutting samples and 8 oil samples collected from the two wildcat wells Kapok- 1 and Ximenia- 1, the authors carried out source rock evaluation and oil- source correlation to probe the petroleum potential of the Doseo basin. Due to the effect of the Central Africa Shear Zone, there developed excellent source rocks in semi deep- deep lacustrine facies with a total thickness of up to 500 m, in the Doba, the Kedeni and the Mangara Formations in Lower Cretaceous, Doseo basin. They are all excellent source rocks with high organic matter abundance (TOC>3%), good kerogen type (Ⅱ1~Ⅰ type), but low maturity (0. 4%<Ro<0. 8%). Only some of them locally entered the peak oil generation window. The research results of molecular markers indicate that oil maturity are widely higher than that of source rocks penetrated, therefore, the present petroleum discoveries are all sourced from mature excellent source rocks in the lower Kedeni and the upper Mangara Formations in deep sags. These research results are helpful to guide future exploration, and to get more petroleum discoveries in Doseo basin.