Loosen sediments extensively distributed along the Golmud-Lhasa section of the Qinghai-Tibet Railway can easily been transformed to aeolian sand by strong wind. The loosen sediments are mainly classified as current aeolian deposit, fluvial deposit, activated ancient dunes, alluvial deposit, and lacustrine deposit. Grain size statistical results show that the range of arithmetic mean diameters of dune sand samples are from 1.29 Φ to 3.25 Φ with a mean value of 2.36 Φ(0.19 mm). The fine sands and medium sands (0.1～0.5 mm) are dominant, which make up 49.44% to 99.67% percent in samples. These results are not conforming to the published data on wind-blown sands from other regions of China or other deserts in the world. The very fine sand content is 7.99% and coarse sand is 5.50%. Most of the sand samples are fairly sorted. The range of standard deviation is from 0.3 to 1.26 and the mean value is 0.58. Skewness values is from -0.41 to 0.36, with a mean value of -0.01. Most samples are symmetry and account for 53.57% of the total. Positive-skewed samples account for 12.50% and negative-skewed ones account for 19.64%. Both very positive-skewed and very negative-skewed are 7.14%. Kurtosis values are from 0.56～1.24 with a mean value of 1.00 and most samples are normal kurtosis and account for 71.43% of the total. The statistical results of grain size also show that the grain size characteristics have great difference for different sand sources, which reflect sand formation progress and environmental characteristics.