低畸变大像场望远镜是实现宽波段高光谱成像系统图像数据高精度配准融合的关键。基于解析法和矢量波像差理论，分析离轴三反光学系统的畸变，提出了一种消畸变的离轴三反系统的设计方法通过解析法计算参数，建立同轴三反初始结构，再将初始结构做离轴处理，根据矢量波像差理论作定性分析与调整。给出了离轴三反系统的光学设计实例，系统焦距为1000 mm，穿轨方向视场角为5.6°，沿轨方向视场角为1°，F数为5，通过Zemax软件测得畸变仅为0.0628%。该方法可用于设计航天大视场高分辨率成像光谱系统的望远镜部分，也可应用于各种要求低畸变的场合。

The low-distortion, large-image-field telescope is the key to the precise image fusion and registration of wide-band hyperspectral imaging system. Based on the analytical methods and vector aberration theory, the distortion of the off-axis three-mirror optical system is analyzed. A new method to design the low-distortion off-axis three-mirror optical system is proposed. A coaxial three-mirror optical system is designed by analytical methods and then the original system is made off-axis. Then the system is optimized according to analysis based on the vector aberration theory. An optical system is designed which is characterized by the system focal length of 1000 mm, cross track field of 5.6°, along track field of 1° and F number of 5. The maximum distortion measured by Zemax software is only 0.0628%. This method can be applied to design telescopes not only in the large-field and high-resolution imaging spectrometer system, but also in the occasions that demand low distortion.