In order to find out the propagation characteristics of lightning wave in coaxial cable,the transit response theory of coaxial cable was used to figure out the transit response to the 1.2/50 μs lightning wave.Besides,the related experiment was carried out under the help of lightning current generator.The research results show:the terminal signals of the coaxial cable are determined by both features of signal frequency and terminal impedance;the high-order modes are caused by the refraction and reflection of lightning wave and its excitation when the terminal is opened;the high-order modes excited by lightning wave mainly concentrate on the wave front because of the influence of the lightning wave spectrum;the final waveform at the terminal is the sum of all the high-order modes,and the lower of the lightning wave front the less of the high-order mode.The distortion of the lightning wave should be considered when propagating in coaxial cable,which has significance in guiding the suppression methods of overvoltage in coaxial line.