Objective To study the relationship between the length of cross-wind-board of nozzle in gravure printing and the heated air filed, in order to improve the hot wind utilization efficiency of the drying system. Methods The wind filed of drying nozzle with different length was analyzed through fluid simulation calculation. Trajectories and pressure distribution were taken as the evaluation parameters to study the fluid field, and the variation rules of vortex, trace and pressure distribution with the length of cross-wind-board were analyzed. Results It was found that cyclone became closer to the substrate surface and trajectories became more concentrated with the incensement of length of cross-wind-board. Meanwhile, the pressure decreased slightly and the distribution was more uniform. Conclusion It was proved that the cross-wind-board could improve the utilization efficiency of hot wind and make the distribution of wind field on the substrate surface more even. This work provides theoretical reference for the structural design and optimization of the drying nozzle in gravure printing machine.