The deformation behaviors of distinct structures respectively located at columnar and equiaxed crystal areas of as-cast Udimet 720Li ingot were investigated in the temperature range of 1050 to 1170℃ and the strain rate from 0.1 to 10s-1 with the deformation degree of 50%. Flow models for the two structures were well constructed separately and contrasted. The flow stress gaps between the two typical structures were various at different deformation conditions in spite of similar apparent activation energy, which resulted from the combined effect of different structure morphologies and dynamic softening behavior. The distinctions of dynamic softening behavior between the two typical structures were discussed systematically.