Abstract: Loess is widely distributed in the Ili Basin, affected by the westerlies, and loess landslides are highly developed. Studying the shear strength and deformation characteristics of unsaturated loess in the Ili Basin under different matric suctions is of great significance. In this paper, undisturbed loess from the Ili Basin in Xinjiang was taken as the study object, and mineral formation analysis and physical property tests were conducted. The consolidated undrained shear test with controlled net confining pressure and constant matric suctions was carried out on the loess samples from the Ili Basin using the Model TFB-1 unsaturated soil stress-strain controlled triaxial test apparatus. The results show that: (1)In the range of matric suction measured by the test, the higher the net confining pressure, the more obvious the hardening characteristics of the stress-strain curve of the sample, and the sample basically shows bulging deformation during the shear process. Under conditions of high matric suction, the stress-strain curves tend to exhibit a softened mode, and the samples are prone to shear failure. (2)The sample's volumetric strain is affected by net confining pressure and matric suction. With an increase in net confining pressure, the volumetric strain tends to shrink. Under conditions of higher matric suction, the peak dilatancy of the volumetric strain is larger, indicating stronger dilatancy characteristics. (3)Matric suction affects the shear strength parameters of unsaturated loess. The cohesion of the two kinds of samples showed a good linear growth trend with the increase in matric suction. The effect of matric suction on the internal friction angle is relatively low. With the increase in matric suction, the growth rate of the internal friction angle of silty clay samples decreases and tends to 0, while the internal friction angle of silty samples shows no evident change. The experimental results of this study can provide mechanical parameters and theoretical support for the study of the formation mechanism of loess landslides in the Ili Basin.