Abstract: The strength of geomaterials has been a hot research of the rock and soil mechanics. Based on the true triaxial tests on variety of different structural intact loesses, the influence of structural change on the strength of the intact loess is analyzed. The results show that the influence of changes of dry density on the structural strength of intact loess is greater than that of change of moisture content under low moisture content; on the contrary, the influence of change of the moisture content on structural strength of intact loess is greater than that of change of the dry density. When the strength of structural loess is greater, the failure line in the -plane of structural loess is closer to the rounded crooked triangle. Conversely, when the strength of structural loess is smaller, the destruction line of the structural loess in the PI plane is more close to the rounded triangle. With the increase of structural effects, the structural loess failure line in the -plane of structural loess changes from the rounded triangle to the rounded crooked triangle gradually, and it eventually tends to Mises circle. With the increase of the principal stress ratio b, the friction angle #x003c6;₁₃ of various intact loesses decreases weakly, and the internal cohesion c first increases and then decreases.