针对1.2 m微晶主镜, 提出了基于6套柔性切向杆机构的侧向支撑与基于18点半柔性Whiffletree机构的轴向支撑相结合的新型主镜支撑方案，用于保证该主镜在较大温差范围以及不同俯仰角度下始终保持良好的面形精度及较高的系统刚度。 分析了该机构的工作原理，实验测试了主镜的面形精度及支撑系统的模态。机构分析表明该支撑方式可有效保证主镜定位精度和面形精度，并具有热解耦能力; 有限元分析确认系统具有良好的支撑性能; 面形精度检测得出主镜光轴垂直面形精度RMS达15.25 nm，光轴水平面形精度RMS为20.75 nm，模态测试则获得主镜支撑系统的一阶固有频率为60.3 Hz。实测结果验证了该新型主镜支撑系统具有良好的面形保持能力及支撑刚度，分析结果与实测结果符合度较好，主镜光轴垂直和水平状态面形精度RMS的相对误差分别为14.0%和17.8%，一阶固有频率相对误差为10.8%。得到的结果验证了有限元建模及分析的可信性，支撑系统设计方案的合理性及相关理论推导的正确性。

For a 1.2 m Zerodur primary mirror, an effective primary mirror support system was proposed. A lateral support based on 6 sets of flexible tangent link structures and an axial support based on 18 sets of semi-flexible Whiffletree structures were combined to ensure the primary mirror to maintain good surface figure accuracy and system stiffness at a larger temperature range and different elevation angles. The working principle of the system was analyzed and the surface figure accuracy of the primary mirror and modal of the support were tested. The analysis for system structure indicates that the support system ensures the positioning accuracy and surface figure accuracy of the primary mirror and its thermal decoupling ability is verified by support principle deduction. The finite element analysis (FEA)on the statics distortion and thermal distortion of the mirror surface shows that the system has excellent structural rigidity. The surface figure accuracy tests indicate that the RMS values of mirror optical surface distortion at the optical axis in vertical and horizontal states are 15.25nm and 20.75 nm respectively. Furthermore, the first natural frequency of support system is measured to be 60.3 Hz at modal tests. As comparing FEA simulation results with measurement results.It shows that relative errors of the mirror optical surface distortion are 14.0% and 17.8% separately at different elevation angles, and that of the first natural frequency is 10.8%. Due to the approximate results between simulations and measurements, it demonstrates that the design scheme and principle deduction of primary mirror support system are reasonable, and the FEA modeling is creditable.