Dust deposits have been widely developed in the middle and lower reaches of Yangtze River since the middle Pleistocene age. These regional dust deposits, known as Xiashu loess in a broad sense, are typically represented by "Jiujiang Xiashu loess", "Anhui Xiashu loess" and "Nanjing Xiashu loess". Their depositional age and sedimentary properties have been clarified, but their provenance remains controversial. Geochemical characteristics of the Xiashu loess was analyzed in this paper and compared with loess of red earth from CLP. Results are stated as: 1) The Xiashu loess in the middle and lower reaches of the Yangtze River was not derived from far north of China, and there are significant differences in the origin of loess from Jiujiang, Anhui and Nanjing areas. The role of dust from North China has been greatly overestimated in the past. 2) During glacial periods, the climate of the middle and lower reaches Yangtze River region was generally deteriorated. The large area of desertification and thick dust deposition in the above-mentioned region represents a respone of the modern subtropical humid monsoon climate zone to global climate change. These were the result of detrital materials transported from proximate upwind fluvial plains by winter monsoon under special topographic and climate conditions. But the effects of regional geomorphology have not received due attention in the past.