Abstract: Loess is a typical unsaturated soil, of whom shear strength is an important mechanical property. In order to investigate the unsaturated shear strength characteristics of compacted loess, a series of trixial consolidated draining shear tests(CD test) were conducted on compacted L₆ loess of Yan'an, using GDS unsaturated soil triaxial apparatus. The saturation, volume and moisture change of compacted loess were analyzed, and the influence of matric suction and net confining pressure on the stress vs strain relation of compacted loess was discussed. It is found that:The deviatoric stress vs deviatoric strain curves exhibit hardening type, and the volume strain is shear shrinkage at the beginning and then change to dilatancy. Both matric suction and net confining pressure have significant influence on the deformation and strength characteristics of compacted loess, Under the same matric suction condition, the higher the net confining pressure, the higher the strength of the compacted loess sample, the larger the peak value of the shearing shrinkage, and the smaller the dilatancy. As the net confining pressure is constant, the bigger the matric suction, the is stronger the soil strength, the more obvious the dilatancy.