Regional biostratigraphic investigation of the Maokou Formation leads to the proposal that a rapid crustal uplift and doming prior to the eruption of the Emeishan basalts. This conclusion is also supported by spatial distribution and sedimentologic features of clastic rocks beneath the Emeishan flood basalts. Clastic rocks are distributed in the flanks of the domal structure. A lowstand submarine fan is found in the northwestern flank, at Pinchuan, Yanyuan county, which is mainly consisted of sandstone and conglomerate. A 60-120 m layer of conglomerate cemented by lava is discovered in the northeastern flank of dome, which is alluvial gravel fans formed as a result of rapid differential uplift. Gravels of the conglomerate at Xishan, Kunming are round in shape suggesting that they may be derived from sediments of paleocanyon. It is argued that clastic sediments are responses to uplift of mantle plume, which also caused emergent trend in facies and karst relief on erosion surface. These data not only confirm the plume initiation model for generation of the Emeishan flood basalts, but also deepen understanding of tectonic in western margin of Yangtze craton in late Permian.