Abstract: In Lower Cambrian, thick sandy and muddy flysch deposits were distributed in southwestern Jiangxi Province. The matrix of the sand possesses more than 15%, and hence most of the sand is greywacke. This paper is focused on the compositions and assemblages of major, trace and rare earth elements of greywacke in Ganzhou, Jinggangshan and Pingxiang. Studies show that the greywacke has relatively high SiO2 content, high Al2O3/(CaO+Na2O)ratios and K2O/Na2O ratios, and comparatively low Al2O3/SiO2 ratios and Fe2O3/MgO ratios as well as lower CaO content. The trace earth elements are similar to those in the upper crust of eastern China, with the enrichment of the large ion radius elements. The rare earth elements are characterized by rich LREE and obvious negative Eu anomaly. It is held that the provenance was from Cathaysia Block. Geochemical characteristics indicate that the northern edge of this area belonged to a passive continental-margin tectonic environment. The sea water somewhat got deeper from south to north.