A 400 cm long core from Tengger Nuur of the Inner Monglia Plateau was collected and grain size, carbonate-content, TOC-content, metal elements and ratios analyzed in the environmental lab of Lanzhou University. A warm and dry palaeocliamtic environment was prevailed during the mid-Holocene (~9 000~4 500 cal.a B.P.) with high lake level and low effective humidity. The lake remained high in the Early Holocene as summer monsoon strengthened with high rainfall and temperature. The lake approached its highest level about ~8 000~6 200 cal. a B.P.. After 3 000~4 500 cal. a.B.P., palaeoclimate turned dry and cold, and the increase in effective humidity was in favor of vegetation in this area. However, with decreasing rainfall, the lake shrank gradually until it dried up.