Abstract: Wireless channel modeling is an important step in analyzing and evaluating the characteristics of wireless communication systems. In order to meet the communication requirements of the next generation of rail trains, this paper studies the radio transmission channel of trains running in tubes under vacuum tube environment based on the propagation graph channel modeling theory. Combined with Lambertian scattering model and geometric diffraction model, three cases of line-of sight transmission, single reflection path and single reflection plus diffraction are considered in the simulation process. The channel transmission matrix under the condition of multiple-input multiple-output (MIMO) is simulated, and the power delay spectrum, K factor, Doppler spectrum and channel capacity are extracted and analyzed when the train is in different positions. The proposed model is helpful to analyze channel fading characteristics and channel capacity of MIMO system in vacuum tube scenarios.