Abstract: The isothermal forging process of blades of a β-γ high niobium containing Ti Al based alloy was simulated by using a Deform-3D software,with focus on the analysis of the effective strain,effective stress and temperature distributions. The results demonstrate that the effective strains of the blade body and rabbet uniformly distribute during the isothermal forging process. With the increase of top die speed and preheating temperature,the effective stress decreases and the dynamic recrystallization is easy to take place. The preheating temperature of 1250-1300 ℃ and the top die speed of 1.0-1.5 mm·s^-1 help to improve the quality of the forged blades.