Huangqihai Lake (an inland closed lake, 40°41 '?41°43'N,112°49'?113°40'E) in the southeastern edge of Inner Mongolia, is located at the north boundary of East Asian summer monsoon. The climate of this area is typical arid to semi-arid, and the lake level of Huangqihai Lake is 1268m a.s.l. A 250cm-deep profile was obtained at Baitaigou (40°50'02"N, 113°22'44"E; 1280m a.s.l.) in Huangqihai Lake area. We studied the 135cm in middle part of the profile (230?95cm) and 90 samples (at 1.5cm intervals) were collected. 5 AMS ~(14)C dates in the 135cm-deep profile demonstrate that the lacustrine layer (230 ?100cm) is from 3580 cal.a B.P. to 1630 cal.a B.P. (Mid-Late Holocene). Based on high resolution proxies of pollen, charcoal (ф>50mum) content, elemental geochemistry and grain size analysis, the climatic evolution of Huangqihai Lake region in Mid-Late Holocene was reconstructed. Our data suggest that the climate of the Huangqihai Lake drainage was drying from 3580cal.a B.P. to 1630cal.a B.P., which is indicated by the following aspects. (1) From 3580cal.a B.P. to 3000cal.a B.P., the lake level of Huangqihai Lake was above 1291m a.s.l., 23m higher than the modern lake level. The lake level reached its maximum at around 3380cal.a B.P., and decreased afterwards. The lake level fall coincides with a transition to a colder and wetter climate,as deduced from vegetation changes (coniferous and broadleaved mixed forest to coniferous forests dominated by Pinus). (2) During a 100 years period around 3000 cal.a B.P., the Huangqihai Lake region underwent fast cooling and drying, accompanied by a rapid shrinkage of lake and change of vegetation type to grassland. During the subsequent 1400 years, climate changed to be dry and warm gradually. Around 1630 cal.a B.P., the Huangqihai Lake fell to a lake level less than 9m higher than the present lake level, and never reached this height since then.