The mechanical behavior and permeability (K) of coal reservoirs are important research directions in the development of coalbed methane recovery. In this study, the raw coal was collected from the Baode block, China. The pseudo-triaxial tests examined the coal mechanical behavior and K under high temperature-pressure (T-P) conditions. We proposed a new micro-slope method to accurately distinguish the deformation stages of coal under high T-P conditions. The whole deformation process is divided into five stages, and the dynamic permeability is divided into six stages. The results show that the K is closely related to the deformation stage and exhibits a U-shaped change with the axial strain, and its minimum value occurs at the end of the elastic deformation. The T and P control the evolution of coal mechanical behavior and K. The peak stress (σmax) and peak strain (εmax) decrease with the T but increase with the P. The initial permeability (K0) decreases with the increase in P and T in the 10–30 MPa and 30–80 °C range, respectively. On the other side, the minimum permeability (Kmin) is least affected by the T and P. The kinetic properties of energy dissipation show that, the T and P control the dynamic changes of K by affecting the energy at different stages inside the coal. This study provides a reference for understanding the mechanical behavior of deep coal reservoirs.