Efficient, economical and environmentfriendly defoaming technology is the basis for achievement of foam drilling fluid recycling. A novel rotary and spray type of foam breaker was designed according to the gas ejector principle by which compressed air was used as the power medium combined with vacuum negative pressure, impact shear, aerated saturation and pressure diffusion for quick defoaming and foam fluid recycling. The computational fluid dynamics software FLUENT was employed to simulate the flow characteristics inside the foam breaker. The simulation results showed that the rotary and spray type of foam breaker generated two adjacent overlapping vacuum negative pressure areas inside and can produce great suction force on the outside flow with the suction amount about 1.6 times the compressed air at the inlet. The maximum negative pressure can reach 21kPa inside of the foam breaker when the mass flowrate of the compressed air flow at the inlet was 0.1kg/s, generating a larger area of negative pressure near the collision point of multiple jets from the converging nozzles due to jet speed boost which is conducive to defoaming.