Abstract: The triaxial shear test in a constant suction is conducted using whole translation method. The relation between mad-made structural loess suction and confining pressure is studied. The undisturbed loess suction is measured using a soil suction measuring apparatus. The structural loess suction is studied when the moisture content and saturation degree change. The test shows the suction decreases gradually when the confining pressure of the triaxial shear increases and, the moisture content of undisturbed loess apparently influences the suction, the suction is decreased along with the increasing of loess moisture content.