Abstract: The spray system is the main component of an icing wind tunnel.It costs a lot to measure water droplets characteristics directly in the test section of an icing wind tunnel.In this paper,a means,including both experimental and numerical method,of studying the droplet dis-tribution in the icing wind tunnel test section is proposed.The droplet distribution characteristics at the nozzle exit are obtained by setting up an independent experimental system based on which the numerical method is used to calculate the movement and mass/heat transfer process of differ-ent droplets in the wind tunnel.Then the diameter and mass fraction of different droplets after e-vaporation can be obtained.The distribution characteristics of droplets in an icing wind tunnel with 3m×2m test section under typical conditions are investigated,and the effects of air humidi-ty is explored.The results show that:(1)the droplets at the nozzle exit and in the test section are in an approximate normal distribution,the MVD in the test section is close to the initial value at the nozzle exit,and evaporation does not cause a significant change in MVD.(2 )generally speaking,the smaller the absolute humidity is,the greater the evaporation of water droplets is. Though,when the absolute humidity is 100%,the MVD of droplets in the test section is smaller than that when the humidity is 70%.The research results can provide a good technical basis for the design and use of an icing wind tunnel.