Abstract: Simulation and analysis were conducted on the flow field and droplet trajectory in a boiler chimney with and without swirl vane using CFD software combined with RANS equations, RNG k-ε turbulence model and discrete phase model, based on which, the effects of following factors on the flow field and dehumidification efficiency of the chimney were analyzed, such as the vane elevation, installation height and stage number, etc. Results show that by comprehensively considering the pressure loss and dehumidification effect, the optimal swirl vane would be of the single-stage kind, with a vane elevation of 45° and an installation height of 30 m.