在高功率固体激光器的终端光学组件中，为了提升三倍频转换效率，对大口径薄型KDP晶体采取两侧支撑的夹持方法，并利用有限元分析软件建立了夹持系统的仿真模型。在此基础上，计算分析了晶体以不同倾斜角度放置时，支撑条数目和长度等夹持系统结构参数对晶体附加面形、相位匹配角及三倍频转换效率的影响。研究结果表明：晶体两侧支撑条总数为4时，大口径薄型KDP晶体附加面形的峰谷值和均方根值、晶轴变化的平均值和三倍频转换效率随支撑条长度的变化不大，且可获得理想的三倍频转换效率。解决了反复调试KDP晶体面形质量的问题而缩短了工程装校时间。

In final optics assembly of high-power solid-state laser, in order to improve the third harmonic generation (THG) efficiency, the method of both sides support for ultra-thin KDP crystals with large-aperture is adopted, and simulation model, is built using finite element analysis software. On this basis, the influence of parameters of clamping system including the number and length of support bars on the additional surface shape of KDP crystals, phase matching angle and THG efficiency are calculated and analyzed for the case of KDP crystals placed at different tilt angles. The results show that, when the number of support bars is four, the peak valley (PV) and root-mean-square (RMS) values of additional surface profile of ultra-thin KDP crystals with large-aperture, the mean value of crystal axis and THG efficiency almost keep unchanged with the length of support bars and an ideal THG efficiency is achieved. Consequently, the problems of repeating test on the quality of KDP crystals′ surface profile can be solved, and the time for engineering assembly and calibration can be reduced.