The Hanjiang River is the biggest tributary of the Yangtze River and it will supply water resource to Beijing through the national South-to-North Water Diversion Project". Field investigations were carried out along the upper reaches of the Hanjiang River. The typical Holocene eolian loess-soil sediment profile (490cm) with interbedded palaeoflood slackwater deposits ( SWD ) was found at the Liaowadian site ( 32°47'8.27〃N,110°42'13.90"E;160m a.s.l) located on the first terrace of south bank of the Hanjiang River in the Yun County, Hubei Province. 98 samples of soil were taken every 5cm continuously down the LWD profile and the samples for optically stimulated luminescence ( OSL) dating were also taken by using steel tubes from the profiles at the same time. After all of these samples were air-dried in the indoor environment for two weeks, all of experiment was done in the environment change laboratory of Shaanxi Normal University. Comparing and analyzing with the curves of particle-size distribution, magnetic susceptibility, loss on ignition, hygroscopic water and Rb/Sr ratio, the results showed that the content of clay, content of fine silt, clay/coarse silt ratio, magnetic susceptibility, loss on ignition, hygroscopic water and Rb/Sr ratio varied regularly in the Holocene loess-palaeosol profile, and the content of these oxides reached the highest in S_0(23.40%,18.70%,0.47, 76.4* 10~(-8)m~3/kg,3.69%,1.35%,and 1.10) and the lower in the loess, including L_0( 19.60% , 17.80% , 0.43, 38.5 * 10~(-8) m~3/kg, 2.98% , 1.17% , and 0.90),L_t (18.20%,16.60%,0.37, 37.4* 10~(-8)m~3/kg, 2.98%,0.89%,and 0.90) and L_1( 15.70%,15.20%,0.33,28.8* 10~(-8)m~3/kg, 2.65%,0.57% , and 0.80). However, fine sand and coarse sand reached the lowest in S_0(5.82% and 2.56% ) and the higher in the loess, including L_0(9.49% and 7.13% ),L_t( 10.70% and 4.87% ) and L_1 13.50% and 7.76% ). The change of the indexes showed the climate and pedogenic environmental changed since the Holocene. The study results indicated that the climate was warm and wet, and the precipitation is abundant and the pedogenesis was stronger in the period of the palaeosol formation. In the stage of the loess accumulation, the climate was cold and arid, so the weathering pedogenesis was very weak. Combined with the observation of gross feature field and experiment in laboratory,SWD lied between topsoil ( TS) layer and Holocene loess (L_0) layer was determiend as the palaeoflood slackwater deposits,the curves of the various index content appeared abrupt shift and the amplitude was lager (6.89%,5.81%,0.23, 65.7* 10~(-8)m~3/kg, 1.55%,0.33%,and 0.50) and (28.30% and 28.80% ),Which indicating the SWD was be product for a dramatic climate mutational event and was barely affected by pedogenic modification and biological activity. In combination with the stratigraphic correlation, archaeological dating and OSL dating, Malan loess L_1 has been accumulated in the last glacial period ; the transitional loess L, has been accumulated in the Early Holocene (11500~8500a B.P.) ; the palaeosols ( S_0) has formationed in the Middle Holocene (8500 ~3100a B.P.) ; Holocene loess L_0 has been accumulated in the Late Holocene (3100a B.P. so far) , the extraordinary palaeoflood events recorded by SWD were dated to 1810~ 1710 a B.P. (200~300A.D.),which is equal to the Eastern Han Dynasty to Wei Jin Era (25~316A.D.) , indicating that a dramatic climate change event for the upper-Hanjiang catchment occured in the end of Eastern Han Dynasty during the Late Holocene, and which causing catastrophic floods in the upper-Hanjiang catchment.