Using the 1D/3D co-simulation method, aiming at the proposed heating scheme of the air conditioning system of the EMU, a 1D model of the heating system and control logic was built in the 1D simulation software Amesim. In the 3D simulation software STAR-CCM+, the 3D model of the ventilation system and the passenger room was built. The heating performance of the scheme and the temperature uniformity of the passenger room was verified through co-simulation. The results show that, compared with 1D simulation or 3D simulation alone, 1D/3D co-simulation integrates the previous independent models and can take into account the parameter performance and structural characteristics of the simulation object. It is more intuitive to observe the transient changes of each part of the system during the simulation process to realize the control of each part of the heating scheme, discover design omissions in advance, and improve the design efficiency, which is of positive significance.