Abstract: Heqing-Eryuan area is located in the western Yangtze Block, and adjacent to Sanjiang juncture zone in the west, which has been undergoing a complete basin-mountain conversion from Late Permian to Late Triassic. Combining with the tectonic events, the researchers in this paper analyzed the stratigraphic lithology and sedimentary environment, and revealed the temporal pattern of basin-mountain conversion and basin sedimentary responses of each stage. The results show the basin evolution of this area can be divided into 3 stages: The intraplate rifting basin stage, the depression basin stage and the foreland basin stage. The huge thick basalt deposition was formed during depression basin stage, and Qingtianbao Formation clastic rocks and Beiya Formation dolomite and limestone was successively formed during rifting basin stage. Besides, the unconformities and hybrid conglomerates were formed in Zhongwo Formation and Songgui Formation during foreland basin stage. This work has scientific significance for the research of basin-mountain conversion in the western Yangtze Block and Sanjiang juncture zone.