The dehumidification system of the main cable is a significant component in the design process of main cable of suspension bridge, which directly affects the service life of the main cable. The influence of different steel wire stacking states in the main cable on the air flow characteristics inside the main cable was systematically studied based on the CFD numerical calculation method, and the actual bridge test of Nansha bridgre (Humen No.2 bridge) was carried out to verify the numerical calculation results. The test results demonstrate that the relative error between the homogeneous pressure drop obtained exploit numerical simulation and the measured pressure drop is less than 5%, indicating that the established model has acceptable accuracy. The existence of the loose structure can effiectively change the velocity distribution on the cross section of the tube. The velocity increase rate of each porosity reaches the maximum value at 0.03D in double stacking state, and the velocity in the cable increases by 12.9% compared with that in single stacking state. The looseness of the loose packing structure has no obvious effect on the turbulent kinetic energy in the tube, while the two-state stacking structure will make the turbulent energy in the tube change more dramatically and the peak value of the turbulent kinetic energy is larger compared with the homogeneous packing structure. Different porosity has no apparent effect on the pressure drop distribution inside the pipeline, Compared with the homogeneous states, the maximum pressure drop in the double stacking state at ? =24.5 is only reduced by 26Pa.