Abstract: Ninety four samples from surface of typical barchans chains on the right bank of the mid-Xiangshui River in the Xiliaohe Plain were collected along the prevailing wind direction. Distribution law of grain size was studied by Laser particle analyzer. Combining with field observation, the results were obtained as follows: (1) The sand dunes and interdunes on the right bank of the mid-Xiangshui River are mainly composed of medium sand, and it is fine sand for that in the bottom of valley. (2) The grain size of dunes adjacent to the valley appears thinner from stoss toe to the summit, while the grain size of dunes away from valley appears coarser from stoss toe to the slope top. The sorting becomes much better from both upwind and downwind toes to the dune tops. The skewness and kurtosis of sediment on the tops of dune are primarily larger than on the toes. (3) Due to the aeolian-fluvial interactions, sand dunes near valley can obtain rich sand source from underlying strata. However, downwind dunes acquire sand from interdunes and drifting fine sand by wind.

Key words: stoss slope, lee slope, grain size composition, grain size parameters