Abstract: For the purpose of guiding the dynamic optimized design of side slope parameters of internal dump more effectively, referring to practice of Huolin River South Open-pit Mine, the limit equilibrium method has been utilized to analyze the effect of side slope height,side slope angle,base dip angle and fault throw, and thus the understand of regularity, to the side slope stability of internal dump. The results have then been applied to the design of internal dump side slop of Huolin River South Open-pit Mine with the numerical modelling, so that the verification and following summary are gained: With the gradually increment of dump propulsion distance, the potential slip position of slope will change. Sliding from the upper slope along the bottom of the lower slope would transfer to be sliding along the upper plate base from the lower slope. The side slope height,side slope angle, base dip angle perform negative linear correlation with the side slope stability; Therefore, with the increment of fault throw, the stability would firstly reduce and then raise, which is completely contrary to the relationship to fault relative slope foot distance L; The stability would reach the minimum under the condition of side slope height,side slope angle and base dip angle equal to 216 m, 20° and 5° respectively; With the difference of fault throw, the distance L, which results in the change of potential landslide mode of dump slope, has also shown difference and increases along the increment of fault throw. As a result, the spatial form of internal dump side slope in downdip undulating basement is clear.