Abstract: To definitely investigate the nature of fracture generation and the mechanism of temperature-pressure coupling in the cracks evolution process of coal mass, we analyze the effect of temperature, pressure, temperature-pressure coupling on coal fracture in this paper; combining damage theory and fracture criterion, we build temperature-pressure coupling model, and illustrate the coupling mechanism from theory and mathematical relationship. The nature of coal under temperature-pressure coupling failure can be described using the principle of first damage and then following the failure criterion.