Abstract: The impact torisonal buckling of elastic cylindrical shell with imperfection studiedon the base of B-R kinematic criterion. It is shown that the impact buckling on the meaning of B-R criterion does not exist with the imperfection's increase and the decrease of the acting time of the torsional impulse. Also it is found that with the decrease of the acting time of the torsional impulse,the buckling wave number increase,but the amplitude of the imperfection has no effect on the buckling wave number.