Permian is an important stratum for the development of marine source rocks in the Sichuan basin, which is of great significance for natural gas exploration. Based on the comprehensive analyses of wells, logging and outcrop data, the stratigraphic boundary between the Middle Permian and Upper Permian in the key wells in the northern Sichuan basin has been redefined. It is confirmed that thin- layer carbonaceous and siliceous mudstone in the Gufeng Member of the Middle Permian Maokou Formation is developed widely in the northern Sichuan basin. Through systematic sampling and analysis of wells and outcrops, the thickness distribution, geochemical characteristics and control factors of high- quality source rocks in the Gufeng Member are identified, and their hydrocarbon generation potential and contribution to gas reservoir formation are evaluated. The results show that: ① the thickness of the high- quality source rocks in the Gufeng Member is mainly 5~40 m, which is in the NW- SE zonal distribution in the northern Sichuan basin, and there are four thickness centers. ② The TOC of the source rock in the Gufeng Member is extremely high and varies widely, ranging from 0. 5% to 31. 04%, with an average value of 5. 08%, indicating it to be a high- quality source rock. The type of organic matter is mainly type II, and the maturity of organic matter is in the stage of maturity over maturity. ③ The deep- water sedimentary environment, strong reducing conditions and high paleoproductivity of the rifted depression in the platform against the background of extensional structure jointly control the development and distribution of high- quality source rocks in the Gufeng Member. ④ The high- quality source rocks in the Gufeng Member have great potential for hydrocarbon generation, with the hydrocarbon generation intensity mainly distributed over 5×108~25×108 m3/km2, reaching the standard of forming large and medium- sized gas fields. The high- quality source rocks in the Gufeng Member are of great significance for the exploration of marine conventional natural gas and shale gas in the study area.