In order to evaluate the detection accuracy of space target electro-optical surveillance equipment, the effect of Lagrange interpolation algorithm with different orders is analyzed for different data sampling rate equipment and ephemeris true value files with different time intervals. The data test shows that the 5-order Lagrangian algorithm can meet the requirements for the LEO ephemeris file (below 2 000 km), and the 9-order Lagrangian algorithm has the highest accuracy for the MEO ephemeris file (above 2 000 km). Aiming at the calculation of angle accuracy index, a method for calculating the angle mean value is proposed. The experimental results show that the method can measure the mean angle well and provide effective support for the subsequent evaluation of angle indicators.