Abstract: By model test

the ventilation volume was studied through hydraulic parameters. The results showed that the ventilation volume was influenced by two aspects: On the one hand it was the ability of water to accommodate air itself

which was decided by the water depth mainly. On the other hand it was the ability of water to absorb air from the bottom of the cavity

which was decided by velocity at the flip bucket and cavity length. The analysis showed that when the water depth was shallow

the ability of water to accommodate air itself played a leading role in the development of aeration. when the water depth was deep

the ability of water to absorb air from the bottom of the cavity played a leading role in the development of aeration. Based on the test result

an empirical formula of ventilation volume about flip bucket was proposed considering the two reasons above.