Abstract: Debris flow deposits in mining areas feature loose structure and weak mechanical proper⁃ ties，and bear high instability risks under extreme weather and geological disturbances. To clarify the insta⁃ bility mechanism and stability characteristics of west slope debris flow deposits in the mining area，taking No.1 and No.2 deposits as research objects，this paper acquires soil physical and mechanical parameters by laboratory triaxial shear tests. The three-dimensional finite difference method and two-dimensional lim⁃ it equilibrium method are comprehensively applied to conduct stability comparative analysis under natural， rainstorm and seismic conditions. The results show that the overall safety factors of the deposit under three working conditions are 3.914，3.560 and 3.012 respectively，and the deposit maintains an overall stable state. Plastic strain concentrates and local displacement develops at the deposit bottom and rock-soil con⁃ tact zone. Constrained by bedrock，the three-dimensional calculation overestimates the local stability of the slope. Two-dimensional profile calculation indicates that rainfall is the dominant adverse factor. The minimum safety factor of Profile 1—1 under rainstorm condition is 1.027，while Profile 2—2 is in a criti⁃ cal stable state under natural condition with the minimum safety factor of 1.010 under rainstorm condition. The increase of pore water pressure and attenuation of effective stress caused by rainfall infiltration are the main inducing factors of soil instability. Seismic disturbance weakens slope stability，but its influence is weaker than rainfall. The three-dimensional finite difference method is suitable for identifying slope defor⁃ mation concentration zones，and the two-dimensional limit equilibrium method presents obvious advantag⁃ es in quantitative evaluation of local profile stability. The integrated-local coupling analysis method can judge the stability of debris flow deposits more accurately. The research results can provide theoretical ref⁃ erence and technical support for debris flow disaster prevention，slope monitoring and treatment in the min⁃ ing area，and stability evaluation of loose deposits in similar mountainous mining areas.

Key words: debris flow deposit, slope stability, limit equilibrium method, rainfall condition, seismic condition