According to the trace element geochemistry and characteristics of the sediments in the Mawo Karst Basin in Weining County,Guizhou Province,the authors discussed sedimentary environmental changes.63samples of sediments were analyzed. The results indicated that the total rare-earth elements are quite high;there are significant differences between LREE and HREE;LREE is abundant,while HREE is defective.The LREE curve is obviously rightward heeling,while HREE is even, and Eu shows obvious negative anomalies.According to the characteristics of Ce_(anom),layers of HD,G1,N1,G5,N5,G6 and N6 show that the basin is in an oxydic environment,whereas the rest of the layers show an anoxic environment.The performance of the trace elements,the total rare-earth elements,the characteristics of Ce_(anom) indicate the climate change of the Mawo Basin,suggesting that there are three paleoclimatic periods,two obvious cycles and three minor cycles in alternating temperature and humidity.