The prototype observation study is carried out for the valve section cavitation problem of the ship lock，taking the newly built Xijin Second Line Ship Lock as an example，the observation shows that the valve slit type recommended by the valve model at the design stage is adopted for the water filling and draining valve，and the natural ventilation of the valve slit is realized in the prototype，and the maximum ventilation volume for the bilateral opening of the water filling and draining valve is 0.11 and 0.17 m3/s respectively.The effect of valve slit ventilation to suppress the valve section cavitation is remarkable：throughout the during the valve opening stage，the obvious cavitation bubble collapse sound and thundering sound which existed without ventilation are not heard at the top of the gate.Compared with no ventilation，the cavitation noise intensity during the bilateral opening of the valve is reduced by 60% and 82% on average after the valve slit is ventilated.The average noise collected by the sound level meter at the top of the gate during the valve opening process wis 68 and 79 dB respectively.The vibration of the valve boom is significantly reduced after the valve slit is ventilated.The anti-cavitation measures can effectively protect the valve and the valve section corridor from cavitation and ensure the safe and efficient operation of the lock.