Base on the regulatory requirements CCAR25.629 of eroelastic stability, the transport airplanes problem is investigated after icing in this paper. For a lrge amphibious airplane T-tail’s flutter model, crried out flutter numerical analysis and wind tunnel test of different iceing accumulation on wing surface,and damping’s method is usd to extrapolate critical flutter speed. Numerical analysis and experimental results show flutter speed increases with the increase of the ice accumulation,and flutter form is coupled with vertical’s bending and torsion.