Abstract: Taking the gangue dump of Lijiahao Coal Mine as an example, this paper makes a comprehensive study on the stability of the gangue dump slope. For the problem that granular gangue cannot be directly made into samples to test mechanical strength parameters, the mechanical parameters of granular gangue are inverted by simulation software PFC3D, and the shear strength parameters of granular gangue are obtained by lateral compression test and triaxial compression simulation test. Using the shear strength parameters obtained from the experiment, the stability of the gangue dump slope of Lijiahao Coal Mine is analyzed by FLAC3D numerical analysis software. The safety factor is around 1.2. The calculation results show that the slope of the gangue dump is in a relatively stable state temporarily. According to the displacement contour, the protection area should be concentrated in the upper two steps, which can effectively avoid local instability. At the same time, in order to ensure long-term stability, combined with the characteristics of gangue, the corresponding effective control measures are proposed.