In this study, the effects of emulsion properties on demulsification of the phosphoric acid-tributyl phosphate (W/O) emulsion by hydrocyclone were investigated. The droplet size distributions were measured pre and post demulsification. The demulsification performance was evaluated by calculating the average droplet size difference. The results showed that increasing kerosene addition in the oil phase improved demulsification efficiency. As the maximum amount of kerosene added in the oil phase, average droplet size difference could reach about 43 mu m. In each composition, as the stirring rate increased from 3000 to 7000 r/min, the effect of initial droplet size distribution on demulsification by hydrocyclone was not obvious. A model for predicting average droplet size difference was established by dimensional analysis method. By comparing the experimental data with calculated ones, this model is available.