The geomorphologic characteristics of different type of sand dunes in Kumtag desert were investigated.On-the-spot sand samples were collected and the characteristics of grain size were analyzed in laboratory.The result shows: there are various types of sand dunes in Kumtag desert,such as: pyramid dunes(stare dunes),simple linear dunes,network dunes,crescent dunes and featherlike dunes.The majority grain size of sand dunes is 0.25~0.063 mm,and the minority is 0.5~0.25 mm and1~0.5 mm.The grain of each dune is good in sand-sorting,which had been selected by wind.The grain size of pyramid dunes in topside of NE slope is the same as that in downside,and become thicker and thicker from top to bottom in South and WS slope;the grain size of two sides of simple linear dunes are the same,while the downside of south slope is thicker.The grain size of outside network dunes slope is thicker than that inside.The grain size of middle part of crescent dunes is thinner than that on topside and downside;the grain size of featherlike dunes "quill" is same as that in crescent dunes,and grain size of "plume" is alternately changed between thick and thin grains.