Heat transfer simulation and stress analysis under hot state were conducted on the high-temperature shaft of CRC air-cooled intermediate roller crusher. The simulation analysis results indicate that the cooling air duct with turbulent blades has stronger cooling and heat transfer effects. Different boundary temperatures and cooling air flow rates will cause significant and directional temperature differences and thermal gradients in the high-temperature axis, resulting in significant additional thermal stress. By importing the hot state model into stress analysis software, the influence of thermal gradient on shaft stress was further analyzed. It was found that the equivalent stress of the shaft in the hot state was much greater than that in the cold state. When designing and selecting materials, the impact of thermal gradient stress should be evaluated, and appropriate measures should be taken to reduce or balance the stress.