Abstract: In order to qualitatively and quantitatively analyze the degree of influence of the water load on the stability of fully mechanized caving coal subsidence area, the underground coal mining subsidence area of Hongyanhe Reservoir was taken as the research object, and a three-dimensional numerical model was quickly constructed through Rhino3D-FLAC3D coupling technology. Combined with field experiments, the development characteristics of overburden cracks in fully mechanized top coal caving mining subsidence area and the influence of water load on the stability of overburden rock in coal subsidence area were studied. The results show that: 8712 fully mechanized top coal caving mining subsidence area water-carrying fissure zone as a whole is “saddle” shape, the maximum development height is 138.24 m; the vertical displacement of the surface of coal mining subsidence area increased by 334.7 mm, the development height of the water fissure zone increases by 3.76 m.