Abstract: A series of triaxial shear tests with controlled suction are performed on Q₃ unsaturated intact loess under constant net confining pressure to study the mechanical behavior of unsaturated intact loess over a wild suction range, and the suction is imposed using the axis translation technique and vapor equilibrium technique with saturated salt solution. The influences of the suction and net confining pressure on the strength and deformation characteristics of intact loess are analyzed. The test results show that the deviator stress of intact loess at failure increases with the suction under the same net confining pressure. The intact loess show different degrees of strain hardening or strain softening during the shear process under different suctions. The suction and net confining pressure have obvious influences on the shear dilatancy of intact loess, and a lower suction or higher net confining pressure results in a smaller shear-dilation. The cohesion of strength parameter of the intact loess increases obviously with the suction, while the internal friction angle does not change obviously in low suction range, but increases with the suction in high suction range.