Abstract: Abstract：Cambrian strata of southwestern Jiangxi are composed of a set of sandy and muddy flysch sediments. Controversies have long existed as to the sedimentary-tectonic environment of these strata. Based on the theories of sedimentary geology and lithofacies-paleogeography, the authors combined field investigation with indoor laboratory analysis and recovered the sedimentary-tectonic environment through the analysis of stratigraphic framework, basic characteristics of sandstone and lithofacies. It is supposed that this set of flysch is hemipelagic submarine fan facies rock accumulated rapidly in southwestern Jiangxi Province. The provenance of the submarine fan was derived from Cathaysia Block in southeast Jiangxi and then deposited continually in the continental rise on the northern edge of Cathaysia Block. The sea water got deeper gradually from SE to NW in Cambrian period. The sea level rose at the early stage of the lower Cambrian period and then gradually got lowered.