Superplastic behaviors of coarse-grained Ti-22Al-25Nb alloy were investigated at temperatures ranging of 1213~1263 K and initial strain rate raging of 3.3×10-4~3.3×10-2s-1. The constitutive equation has been established according to the flow stress of the alloy during the deformation process. The results show that the alloy exhibits a certain degree of superplasticity under above conditions. The maximum elongation exceeds 370% at 1238 K and 3.3×10-4s-1. The elongation of the alloy increases with decreasing of strain rate. The average apparent activation energy of the alloy was calculated to be 759.918 kJ/mol. The deformation mechanism of the alloy mainly is dynamic recrystallization and the new phase growth up