<p>Despite the significant advantages of using aeolian sand as fill material in desert road and railway projects, concerns persist regarding its inferior mechanical properties potentially compromising structural safety. For elucidating its mechanical behavior, a series of monotonic and cyclic triaxial tests were conducted on saturated and dry aeolian sands from Taklamakan Desert under different confining pressures and relative densities. The shear strength, deformation and critical state characteristics in monotonic tests, as well as the accumulated axial and volumetric strains in cyclic tests were analyzed. The test results showed that compared to saturated aeolian sand, dry aeolian sand exhibited larger shear strength and dilation in monotonic tests, while in cyclic tests it showed smaller accumulated axial strain. The critical states of saturated and dry aeolian sand were different, with the critical state stress ratio and void ratio of the dry specimen being larger than those of the saturated one. These phenomena indicated that determining the strength and deformation of dry aeolian sand in practical engineering through conventional saturated specimens was conservative. Furthermore, as relative density increased, aeolian sand exhibited significantly enhanced strength and reduced cyclic accumulated strain. The strength and deformation of aeolian sand could meet engineering requirements when adequate compaction was achieved.</p>