In order to explore the water permeability of sand layer and its controlling factors in the Tengger Desert,an infiltration experiment was carried out in the region.The results show that during the first stage before a steady infiltration rate was reached,the moving sand dunes have the highest starting infiltration rate,followed by the half-fixed sand dunes and low-lying-lands in order. After about 6.3~ 8.8 min, the infiltration rate of sand layers became stable.The saturated infiltration rate of half-fixed sand dune was slightly larger than that of the moving sand dune, while the rate of the low-lying-land remained the smallest.The moving sand dune and the half-fixed sand dune had almost same high infiltration capacities and the low-lying-land has the smallest infiltration capacity.As typical characteristics,the sand layers had high and steady infiltration rates and need only a short period from start to approch steady infiltration rates,owing to the coarse but uniform texture and good pore connectivity.The high infiltration rates provided very good conditions for the transformation from rainfalls to groundwater.For the three infiltration models,the Koctakob formula was the best in describing the water permeability of sand layers,the H orton formula the second,and the general formula the most unfavourable.