Abstract: In order to form supercavity at lower velocity and explore drag reduction by supercavity, experiments of ventilated supercavity on symmetrical underwater bodies have been performed in water tunnel. Supercavity has been formed by using ventilation method at lower velocity. By changing ventilation volume and Froude number, different supercavity lengths and corresponding drag coefficients of model have been obtained. Experimental results show that supercavity length increases with ventilation coefficient increasing at constant velocity. Drag coefficient of model reduces initially and then begins to increase slowly as the cavity length increases. Gravity causes strong asymmetry of ventilated supercavity. By comparing supercavity length of upper wall with that of lower wall, the influence of Froude number on ventilated supercavity length has been quantified. The influence can be ignored at Fr >43.74.