In order to study the charging mode of ancient ultra-deep natural gas reservoirs and to discuss the quality, size and lifetime of Marine source rocks in the early Cambrian, the Longwangmiao Formation gas reservoir in Gaoshiti—Moxi area of Sichuan Basin is selected as the research object in this paper. Methods: Combining the regional tectonic evolution history and hydrocarbon generation history of source rocks, using the method of comparing the homogenization temperature of inclusions and burial history temperature, the charging model was established and the source rocks were traced to the Lower Cambrian Qiongzhusi Formation; In this paper, the organic productivity and preservation conditions of Marine source rocks formed in the early Cambrian are analyzed from the perspectives of paleoclimate, palaeoenvironment, paleontology and palaeogeography. Results: The research shows that the formation of ultra-deep gas reservoirs in Sichuan Basin has experienced multi-stage charging of paleo-reservoir, paleo-cracking gas reservoir and late dry gas, and the gas reservoirs come from the gas released from paleo-cracking gas and ultra-late source rock. Conclusions: This fact indicates that the global setting of the Early Cambrian provided the basis for the development of high-quality, large-scale and long-lived source rocks, and provided the theoretical basis for the formation of the Sichuan Basin super gas basin.