Hot forging die bear periodic thermal load and mechanical load during service, and bad work environment makes the service life of dies generally short. Hot forging die damages mainly appear in temperature fluctuation zone, and gradient composite materials cladding process can be used to do surface treatment on homogeneous hot forging die. This process can greatly decrease the peak value of temperature and stress and prolong the service life of hot forging die. FE model of hot forging process under mechanical press was build based on Deform-2D, temperature and stress field of homogeneous hot forging die and FGM surface cladding hot forging die under mechanical press were compared. Then the characters of thermomechanical load based on FGM surface cladding hot forging die were described, which provided foundation for design and manufacture of FGM hot forging die.