In order to reveal the influence law of faults key parameters on activated water outburst under specific geological conditions in Southwest China, taking the Zhenxing Coal Mine affected by F7 fault in Guizhou as the research object, a three-dimensional geomechanical model was constructed by using FLAC 3D numerical simulation software to systematically explore the influence of fault dip angle and fault drop on the evolution of mining stress field and the characteristics of fault activation. The results showed that under the same working face and fault spacing, the greater the fault dip angle, the greater the vertical stress and shear stress concentration, and the smaller the dip angle, the more violent the shear stress fluctuation, which was more likely to induce fault activation. The fault drop had little effect on the peak shear stress, which mainly acted on the stress transfer indirectly by changing the integrity of the fault structure. The change of the drop did not significantly change the overall law of stress evolution, but had a certain influence on the distribution of local stress concentration areas. During the advancement of the working face, the stress concentration area gradually migrated to the fault direction with the shortening of the distance from the fault, and the stress concentration effect was significantly enhanced when the distance was less than 60 m. The research results could provide scientific support for the precise prevention and control of fault water outburst disasters in coal mines in southwestern mountainous areas, and enrich the research system of fault activation water outburst under complex geological conditions.