The measurement accuracy of angle is an important technical indicator of the optical system. The detection method for Angle measurement accuracy with traditional electronic theodolite has less measurement data and single scan-ning direction, which result in the inaccurate measurement results. An Improved detection method is proposed:Adjust the electronic theodolite to make the electric cross imaging field of view CCD by optical system. To scan optical sys-tem all directions in lattice form through rotating the electronic theodolite. Collect electric cross image real-time by CCD. Using retinex based on wavelet transform algorithm to enhancement electric cross image contrast. OTSU was used to segment image,then by the combination of projection method and the binomial curve fitting algorithm,the po-sition accuracy attended sub-pixel level. Using RBF to surface interpolating for electric cross center lattice data, and solve the accuracy of angle measurement based on entire CCD sensor imaging surface. The result show that the mea-suring accuracy can be reached 0.1μrad and the angle measurement accuracy of optical system improved 0.01 mrad,and angle measurement accuracy detection more accurate.%测角精度是光学系统的重要技术指标。针对传统的电子经纬仪测角精度检测方法测量数据少、扫描方向单一导致测量结果不准确，提出了一种改进的检测方法。调整电子经纬仪，使电子经纬仪发射的电十字通过光学系统成像在CCD视场中，旋转电子经纬仪以点阵形式，对光学系统各个方向进行扫描，计算机实时采集电十字图像。对采集的电十字图像，通过基于小波变换的变分Retinex算法增强图像对比度，采用OTSU阈值分割背景和目标，采用投影算法及二项式曲线拟合将电十字中心定位到亚像素级。对最终获取的电十字中心点阵数据通过径向基函数进行曲面插值，解算出基于整个CCD像面的测角精度。实验结果表明：该方法的测量精度达到0.1μrad，测得的光学系统测角精度提高了0.01mrad，检测的测角精度更加准确。
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