介绍了三子镜稀疏孔径双反系统的结构，推导其广义光瞳函数，并阐述三子镜稀疏孔径双反系统的成像原理。对光学系统中的一个子镜分别引入平移误差和倾斜误差，用Zernike 多项式表示这两种误差，并用Matlab 软件对有误差的系统进行模拟成像。提出相对模糊度函数，并用其对成像的质量进行评价，给出随着子镜平移误差或倾斜误差的增大，所成图像相对模糊度的变化曲线，分析子镜误差对系统成像质量的影响。结果表明：三子镜稀疏孔径双反系统子镜平移误差和倾斜误差对系统成像质量造成的影响规律不同，系统所成图像的相对模糊度随平移误差的增大呈周期性变化，随倾斜误差的增大而单调增大，倾斜误差比平移误差对成像质量的影响更大一些。因此，装调时对倾斜误差的控制要比对平移误差的控制更加严格。

The structure of three sub-mirrors sparse aperture two-mirror system is introduced. The generalized pupil function and imaging principle of the system are derived. One of the three sub-mirrors has piston error and tilt error. The errors are represented by Zernike polynomials, which are imported in simulation of imaging with Matlab. Relative ambiguity resolution is advanced to evaluate imaging quality of the system. Through the relationship between the errors and the relative ambiguity resolution, the influence of sub-mirror errors to imaging quality is analyzed. The results show that the impact on imaging quality with piston error is different from that with tilt error. With the increase of the error, the relative ambiguity resolution periodically changes with piston error but monotonically increases with tilt error. Tilt error affects the quality of imaging more than piston error does, so we should control tilt error more strictly than piston error.