Abstract: According to the force on the droplet and droplet physical properties, the droplet physical state was described and the three-dimension single droplet model was established based on the physical description and mechanism research on the droplet movement. The droplet model was applied to simulate the droplet movement in the wave-type vane steam separator, in which the steam fluid field was numerical simulated and movements of the droplets were simulated by calculation procedure. The droplet behavior mechanism in the steam flow field in the wave-type vane was explained.