The air distribution system is one of the key systems for ensuring the safety and comfort of the passenger aircraft. The large number of components poses a severe challenge to the efficiency, accuracy, and convergence of system simulation. For the 3D CFD method, the complex and large number of meshes leads to low computational efficiency. The 1D simulation has high efficiency, but the local accuracy is inadequate. To solve this problem, the 1D Fluid System Simulation Software Flomaster with the linearization algorithm is used to establish the system-level model. The flow characteristic curve is obtained by the CFD (computational fluid dynamics) method for the local irregular ducts and introduced into the 1D system model for iteration. The effects of local flow resistance and thermal insulation on the flow distribution and thermal performance of the system are studied using this simulation model. The results show that the local flow resistance affects the total flow and uniformity of the cabin distribution, the improvement of insulation performance is weakened with increasing insulation layer thickness, and the application of thicker insulation layers on the downstream pipeline is more advantageous to limit the maximum temperature change of the conditioned air.