In order to find the interpretation of the incomplete closure of piezoelectric pump check valve in high frequency, the characteristic of the pump in that working conditions was analyzed, together with the judgment basis and theoretical demonstration of the existence for the phenomenon. The incomplete closure of piezoelectric pump check valve phenomenon was found, and frequency response of the check valve in water was obtained from its dynamic model. The mean force and displacement of valve was calculated in hydrodynamics. Relative reaction of the frequency response and mean displacement were analyzed. Sufficient condition for the check valve incomplete closure was obtained which was amplitude amplification less than 0. 25. The results show that check valve can close completely operating at 80 Hz. When the amplitude amplification less than 0. 25 , the check valve incomplete closure phenomenon was observed at 140 Hz. With further increasing of the frequency, amplitude amplification factor decreases, the phenomenon is more obvious under the condition of low amplitude amplification factor, the minimum clearance between the check valve and valve seat more than 30μm at 260 Hz.%为了阐述压电泵高频工作时其阀的不完全关闭现象,并更好地利用该状态下压电泵特有的优点,分析了此条件下泵的出流机理,从理论上证明了现象的存在性,并得到预测依据.以流体作用在阀上的动压为基础,建立阀在液体中的振动力学模型,得到阀在压电泵工作状态下的频率响应,同时利用流体动力学分析阀在工作液体中的平均受力及位移,通过动态响应和平均位移的相对关系,得出阀不完全关闭的充分条件为振幅放大系数小于0.25.试验结果表明:80 Hz时阀处于可完全关闭状态；140 Hz时振幅放大系数小于0.25,阀的不完全关闭现象出现；随着频率升高振幅放大系数减小,260 Hz时阀的不完全关闭现象更加明显,阀与阀座的最小间距大于30μm.
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