惯性约束聚变频率转换系统中，大口径薄型KDP晶体的面形质量是影响频率转换效率能否达到设计要求的关键因素之一。针对45°放置状态下口径为400 mm×400 mm的三倍频KDP晶体，采用ANSYS有限元分析软件，建立了不同夹持方式和具有不同加工误差的KDP晶体模型和夹具模型，分析了加工误差对不同夹持方式下KDP晶体附加面形的影响，给出了不同加工误差和不同夹持情况下，KDP晶体附加面形的P-V值和RMS值。研究结果表明，夹持方式和加工误差是引起KDP晶体附加面形变化的重要因素，正面压条夹持方式即使在晶体和夹具存在加工误差时也可以较好地控制晶体的附加面形。

In frequency conversion systems of inertial confinement fusion, surface quality of KDP crystals with large dimension and low thickness is one of the key factors influencing the frequency conversion efficiency. For the third harmonic generation KDP crystals with 400 mm×400 mm dimensions and with 45° departure angle from the horizontal plane, finite element models have been built up to analyze the effect of the fabrication errors on the additional surface variations of KDP crystals under different clamping modes, and the P-V and RMS values of the surface variations under different clamping modes and fabrication errors are given. The results show that the clamping modes and the fabrication errors are responsible for the additional surface variations, and the additional surface variation can be controlled by the clamping bars on the front even if the fabrication errors of KDP crystals and clamps exist.