Wetness radius was an important key index to measures the effect of water infusion, the paper used FLUENT to simulate the water infusion wetness radius, compared with the results which from 4102 working face water infusion wetness scope of Pulongwan Mine, It was concluded that water injection pressure of 3 MPa, with wetting radius of about 4 m, the water injection pressure of 20 MPa, with wetting radius 8 m or so, the simulation results agreed with the measured data. Studies showed that FLUENT was an effective way to predict water infusion wetness radius, and provided the basis to ensure the best water infusion drilling interval and improve the efficiency of water infusion.