Quaternary red clay and yellow-brown earth coexist in Xuanzhou, Anhui Province.The former is mainly distributed on eroded hills and slopes; the latter mainly on plain,low hills, valleys and feet of hills. According to the investigations of topographical features and typical soil profiles in this region, it was found that the yellow-brown earth horizon was above the Quaternary red clay horizon. With ESR dating method,the yellow-brown earth was dated to 80 ka B. P., while the Quaternary red clay was 240 ka. B. P Comparative study of basic physical and chemical properties and susceptibility of the two soil-forming parent materials showed that the Quaternary red clay suffered stronger weathering than the yellow-brown earth. It indicated a hot and humid climate in the middle Pleistocence, when the Quaternary red clay was formed,and then the climate turned cold in the late Pleistocence. This change resulted in the halt of red earth development and the formation of yellow-brown earth. The red weathering mantle exposed in this region was considered to be formed under the palaeo-climate in the middle Pleistocence; while the yellow-brown earth was mainly affected by the modern climate.