Abstract: Wedge-shaped loess collapse is mainly controlled by two opposite structural planes. According to the failure mechanism of wedge-shaped collapses, the geomechanics model was generalized. Formulas were established to calculate the coefficient of stability of wedge and two structural planes by combining the limit equilibrium equation, in consideration of Mohr-Coulomb strength criterion, and stability analysis method of wedge-shaped loess collapse was put forward. The research results provided the theoretical basis for quantitative evaluation of stability of loess collapse, and have important reference value for the design and construction of regulation project for loess collapse.