Abstract: The collapse of tunnels under blast impact is a very complicated dynamic process problem, in previous studies, there are not involved wavelengths’ impact on tunnel’s collapse under equal impulse condition.In this paper, numerical simulation method is used to analyze the impact of ground impact loads of different wavelengths on tunnel collapse under the condition of equal impulse.The dynamic response of structures under five different wavelengths and chamber span ratios is calculated.The velocity time history characteristics and the overall plastic strain of key nodes in the structure are studied.The variation rule of area and kinetic energy of collapse area under five conditions is analyzed.The results show that the ground impact wavelength has a great influence on the collapse failure mode of the cavern.The location of the cavern is different when the ratio of the wavelength to the span of the cavern is different.When the impulse value of the ground impact load is fixed, the area of the collapse decreases with the increase of the ratio of the wavelength to the radius of the cavern, and the kinetic energy of the collapse area decreases accordingly.