Abstract: Combining the related study of the Carboniferous prototype basin in Junggar basin, based on the analysis on the data of drilling, logging, seismic, fossil and thin section, and comparing with the characteristcs of the Early Carboniferous marine sediments in Dinan swell, the paper identifies that the Early Carboniferous was the extension period of the Kalamaili Ocean after its subduction. Under the background of the remain ocean after the closing of ocean basin, thick flysch formations which are typical in Well Quan-5 were developed and submarine volcano erupted intermittently. In the massive flysch formation with the thickness about 1 000 m, marine dark shale of the Bouma sequence E and sandstones of Bouma sequence A and B constituted the structures of source rocks interbedded with reservoirs vertically. The geochemical analysis results show that the dark shales are widely developed and has high maturity in the flysch formation and can be considered as relatively good-good source rocks. The understanding not only changes the previous opinion that the low-maturity Carboniferous source rocks in Dibei swell have no exploration potential, but expands the existing hydrocarbon accumulation pattern of near source rocks and controlled by uplifts in Kelameili gas field. A new gas accumulation pattern of source-reservoir integration in tight sandstones is proposed for the Lower Carboniferous strata in Dibei swell, which will be of practical significance for the natural gas exploration in the Carboniferous formation