A large amount of aeolian sand is distributed along the main stream of the Tarim River. Due to the scouring effect of seasonal floods, sliding damage occurs on the river bank. In order to further explore its failure mechanism, the indoor direct shear, compression and penetration tests were carried out to explore the variation law of mechanical properties of aeolian sand under different water content and different dry density conditions. The results show that: (1) Direct shear test: with the increase of water content, the cohesion increases first and then decreases, reaching the peak at the optimal water content. The change curve can be expressed by quadratic function, and the internal friction angle decreases linearly. With the increase of water content, a viscous water film is formed on the surface of the particles. After reaching the optimal water content, the viscosity of the water film is weakened, resulting in a trend of increasing first and then decreasing. The thickening of the water film leads to a decrease in the sliding friction force when the particles roll. With the increase of dry density, the cohesion and internal friction angle increase linearly. With the increase of dry density, the particle spacing decreases, the van der Waals force increases, and the cohesion increases. At the same time, the contact occlusion ability between particles is enhanced, and the internal friction angle is increased. (2) Compression test: With the increase of water content, the compression coefficient and modulus of resilience showed a linear increasing trend. Under the same axial stress, as the water content increases, the water film becomes thicker, the resistance between the particles becomes smaller when the dislocation displacement occurs, the compressibility increases, and the rebound amount increases. With the increase of dry density, the compression coefficient decreases linearly and the rebound modulus increases linearly. With the increase of dry density, the contact between particles is close, the resistance between particles increases when the dislocation displacement occurs, the elastic deformation of the soil contact point increases, the compression deformation decreases, and the rebound amount increases. (3) Permeability test : With the increase of dry density, the permeability coefficient decreases linearly, distributed between 1×10-4 cm / s and 3×10^-4 cm / s, which is 2 to 3 orders of magnitude different from the theoretical value obtained by experience. The traditional theoretical permeability coefficient calculation formula is modified. After eliminating the error caused by the low dry density, the measured value obtained by the test is close to the calculated empirical value, and the whole can be expressed by a linear function. As the dry density increases, the resistance of water molecules passing through the pores between soil particles becomes larger, resulting in a decrease in permeability. The research results can provide reference for the management and maintenance of the Tarim River bank..