Abstract: Based on Euler-Euler two-fluid model and the mechanism of air-fluid phase momentum transfer, numerical simulations of ventilated cavitating flow were carried out under various Froude number and ventilation rate. The variation law of cavity shape and cavitation number was obtained in regard to different working conditions. Compared with experimental results, the numerical model is capable of predicting the cavity shape accurately. By further analysis of the velocity field and interfacial shear stress, it is found that, at low ventilation rate, the interphase slip velocity and shear stress appear stronger, which results an easier air package leakage by re-entrained jet. While at high ventilation rate, the possibility of gas leakage from the interface in the form of small bubbles is enhanced due to a delayed breakup point by re-entrained jet. Above conclusions are coincidence with experimental results and hence the validity of numerical model is proved.