Abstract: The region of Ebinur Lake belongs to the continental temperate climate．Analysis with aerial photos asserts：the surface of Lake is reduced by about 45% from 1959 to 1972 ．The article analyses the two causes affecting the reduction of Lake water：the influence of climatic fluctuation and the human ex-cessive introduction of river water into the Lake．The author purposes the radical way of conserve the Lake：that is to guarantee the river supply and to reduce the cultivated area around the Lake．