Abstract: The maximum water head of Yinpan Lock is 36.46 m. Because of its high water head, the tainter valve and the diversion opening zone are easy to be cavitated. Although the cavitation problem of the tainter valve and the diversion opening zone have been studied in the Three Gorges Project Lock which has five steps, the working condition of tainter valve of this single lift lock is worse while emptying because of its relatively constant water level of downstream; besides, the Yinpan Lock has big navigation stage fluctuation in the downstream, so the cavitation problem can not be solved by embedding shallowly the tainter valve and natural ventilation, and in consideration of the geological factor, the embedded depth of the tainter valve can’t be too big, so it is more difficult to solve the cavitations problem of the tainter valve zone. To ensure the safety of the lock itself and ships, the model scale 1∶20 test was conducted. According to the model test results, we found there existed vacuum pressure in the tainter valve zone and big pressure pulsation in the diversion openings of the design scheme. By optimizing the working mode of the tainter valve and the arrangement of water delivery system, the minimum time average pressure is to be rised to 2×9.8 kPa, some key problems of cavitation of the tainter valve zone have been solved, and it has offered scientific basis to the design.