Ulansuhai Lake is the important component part of irrigation and drainage system in Hetao irrigation region of Inner Mongolia.We applied the attribute recognition method in the summer water quality evaluation of Ulansuhai Lake and divided according to the lake situation.The water quality in every area was analyzed,and the water quality situations in Ulansuhai Lake in 2006 and 2008 summer were gained.It provided the scientific basis for the effective utilization and the pollution treatment of Ulansuhai Lake.