Abstract: The damage of wind-lown sand flow is multiaspect, not only its destruction to soil surface texture and reduction of soil anti-rodibility, but also the affection on air quality and human activities. The Taklimakan Desert is the largest, warmest and driest desert in China, and it is also known as one of the  largest mobile deserts in the world and one of the main source fields of sandstorm in China. So it is of signality to study the structure of wind-lown sand flow. In this paper, the structure of wind-lown sand flow over the Xiaotang area in a desert ecotone in the Taklimakan Desert was studied. The results showed that the proportion of transported sand quantity within a 30-m height was higher than 47.3% of the total transported sand quantity near ground surface, and this result was different from that in previous studies. The transported sand quantity with height above ground surface changed in a power function way. The particle size distribution analysis of windblown sand sediment collected from different soil layers showed that the proportion of fine sand, very fine sand and silt was dominant (>99%). The average particle size was decreased with the increase of height. In windblown sand flow, wind profile near ground surface was not in a logarithmic distribution but in a power function distribution (u=az^b).  

Key words: desert ecotone, ind-lown sand flow, tructure of wind-lown sand flow, ediment discharge, and particle motion, article size, aklimakan Desert