Abstract: In the mining of deep coal seams, stress-dominated coal and gas outbursts occur frequently in environments with low gas pressure and high in situ stress, with gas-containing coal-rock composite structures serving as the carrier. The mechanism of such outbursts is significantly different from that of typical outbursts, posing severe challenges to the safe and efficient production of coal mines. Previous research on this type of gas disaster remains extremely limited. To reveal the macroscopic and microscopic failure characteristics as well as the energy mechanism of such disasters, this study comprehensively adopted true triaxial physical simulation tests and three-dimensional discrete element numerical simulation methods to systematically investigate the instability-induced disaster process of the gas-containing coal seam-roof composite system under different in-situ stress conditions. The research results indicate that the increase in vertical stress, decrease in horizontal stress, and increase in burial depth are the key factors promoting the transformation of outburst types from typical outbursts to stress-dominated ones. This transformation essentially stems from the increase in the vertical-horizontal stress difference and the level of in situ stress. Macroscopically, stress-dominated outbursts are characterized by hole morphologies with “large opening and small cavity, large upper part and small lower part” as well as more complex delamination failure. Microscopically, they exhibit a wider range of microcrack zones, a tension-shear mixed failure mode dominated by tension, and a strong acoustic emission response. Energy analysis shows that the contribution of coal-rock elastic energy in stress-dominated outbursts is significantly enhanced; under high stress conditions, its magnitude can be comparable to that of gas expansion energy, and the two jointly constitute the main energy source of the disaster. Based on the principle of energy conservation, an energy equation for stress-dominated outbursts was constructed by introducing an outburst type discrimination coefficient. This criterion was verified to be reliable through the case of the “4·19” outburst accident at Huainan Dingji Coal Mine. This study clarifies the incubation mechanism of stress-dominated coal and gas outbursts and provides an important theoretical basis for the accurate identification and effective prevention of such disasters in deep coal mines.