The Middle Permian Qixia Formation along Lower Yangtze River in Anhui province is very thick, with high organic content and well preserved condition, the well developed rudstone is also the key attention object. But about the origin of the rudstone has different viewpoints. Undoubtedly, this is an imperfection for reconstruction of the Permian paleogeography and oil—gas exploration along Lower Yangtze River area. Therefore, it is significant to ascertain the origin and sedimentary facies of the rudstone in the Qixia Formation. According to the colour, content, appearance, size and roundness, writers differentiate 4 types of rudstone. Summarizing international understanding of the origin of rudstone and previous study of this area, combining with this study, in depth discussion has been made on the origin of the rudstone. The result showing that the rudstone is formed in slope. In addition, because of the difference of gradient, it respectively developed different gravel shapes, gravel and matrix assemblages, and microfacies' characters. Clinothem facies of the rudstone can be further divided into upper slope, middle slope and lower slope.