Abstract: Existing studies on the deformation and failure characteristics of the floor rock mass in working faces mainly focus on the failure characteristics during the mining disturbance stage, while neglecting the damage and failure of the floor rock mass caused by the unloading of the working face, and thus the results have certain limitations. In actual engineering conditions, the floor rock mass undergoes a mechanical state transition from abutment pressure disturbance to unloading, and the unloading of the working face also induces tensile failure within a certain range of the floor rock mass. To address this issue, the floor rock mass of the main coal seam in the working face 11123 of Pan'er Coal Mine, Huainan Mining (Group) Co., Ltd., was taken as the study object. Based on the different stress states of the floor rock mass during the abutment pressure disturbance stage and the goaf unloading stage, corresponding mechanical models of the floor rock mass were established. Combined with the Mohr-Coulomb criterion and the unloading failure mechanism of the rock mass, the deformation and failure characteristics of the floor rock mass at different stages were analyzed. The results showed that: ① Coal strength, mining intensity, and initial stress all affected the distribution pattern of mining-induced stress, and the mining-induced stress concentration coefficient was negatively correlated with the depth of the plastic zone. ② When the mining height decreased, the advanced abutment pressure increased, and the depth of compression-shear failure of the floor rock mass decreased. When the mining height was 2.5–4.0 m, the compression-shear failure depths of the floor rock mass under the disturbance of advanced abutment pressure were 16.96, 18.02, 18.63, and 19.02 m, respectively. ③ Under unloading conditions, the direction of the maximum principal stress of the floor rock mass before and after unloading remained highly consistent. Greater advanced abutment pressure led to increased unloading magnitude, thereby deepening the tensile failure induced by unloading. When the mining height was 2.5–4.0 m, the corresponding unloading failure depths of the floor rock mass were 21.56, 19.15, 18.03, and 17.74 m, respectively. Field test results showed that when the initial mining height was 3.5 m, tensile strain was first detected at an optical fiber length of 12 m (vertical height 8.5 m), with a peak value of +1 800 με. Continuous compressive strain occurred within the optical fiber length range of 15–37 m (vertical height 10.6–26.2 m), with a maximum value of −1 500 με. The rock mass within the optical fiber length range of 37–57.75 m remained basically stable and was not significantly affected by mining disturbance. Within the vertical height range of 13.2–17.7 m, the current value decreased to 10 mA. Based on comprehensive test results, the maximum failure depth of the floor rock mass was determined to be 17.7 m, which was generally consistent with the failure depth calculated by unloading theory.