Abstract: To effectively prevent and control water inrush disasters induced by floor failure during deep coal mining, this study takes the Xinwen Coalfield as the engineering background. By comprehensively using grey relational analysis, multiple linear regression modeling, the theory of zoning evolution of floor failure, and UDEC numerical simulation, the evolution mechanism of floor failure under multi-factor coupling and its guiding significance for the prevention and control of water inrush disasters are systematically revealed. Grey relational analysis quantitatively identifies that mining depth is the key driving factor controlling floor failure, and its influence on floor failure depth shows a stepwise linear growth characteristic. The multiple linear regression model established based on the Mohr-Coulomb criterion can accurately quantify the nonlinear influence law of working face length and advancing distance on failure depth. For the first time, 140 m for working face length and 240 m for advancing distance are determined as critical thresholds; beyond these thresholds, the growth rate of floor failure depth slows down. UDEC numerical simulation clearly reveals the fundamental transformation of the floor failure mode under the deep high-stress environment: with the increase of mining depth, the failure mode gradually evolves from local shear-dominated failure in shallow mines to complex composite failure (shear-tension-fracture connectivity) in deep mines, eventually forming a connected fracture network with high density and large aperture, which constitutes the main water inrush channel. Mutual verification using multiple methods shows that mining depth dominates the evolution of failure mode and overall failure depth by controlling the stress level. Working face length and advancing distance affect the distribution range and concentration of surrounding rock stress in the stope, significantly accelerating the expansion of the floor failure zone before reaching the critical thresholds, and their effects are constrained by mining depth. The synergistic action of these three factors determines the final morphology of floor failure and the risk level of water inrush. Through cross-validation of multiple methods, the key controlling factors and their interaction mechanisms are accurately identified, and the formation mechanism of the composite failure mode under deep high stress is revealed. This provides targeted critical parameter control criteria and key area identification principles for the prevention and control of floor water hazards in deep mining of the Xinwen Coalfield.