Clay minerals of surface sediments in the salt lakes of Hol Xil area were studied in this paper with the purpose of obtaining some recent environmental information of the lakes. The results show that clay minerals are illite and chlorite in surface sedimentary samples, whereas non-clay minerals mainly include quartz, calcite and feldspar together with small amounts of dolomite, aragonite, amphibole and gypsum. In conclusion, illite and chlorite, as major clay minerals in samples, suggest that the environmental conditions of the studied lake area are arid and cold, whereas small amounts of ordered I/S mixed layers in local districts, i.e.,No.1 and No.3 districts, indicate that these districts have undergone the environment of alternate transient arid and humid in recent years.