In order to improve the angle measurement accuracy of laser seeker, the source of angle measurement error of laser seeker was studied, and the error of direct writing laser seeker calibration system was analyzed. Firstly, the influence of the optical system in the laser seeker and the detector installation error on the angle of the seeker was analyzed. The relationship between the angle of turntable and the angle of seeker under idea conditions was given. Secondly, the working principle of the direct writing laser seeker calibration system was introduced. Thirdly, in order to improve the angle accuracy of the calibrated seeker, the installation error of the calibration system was analyzed. Finally, according the analysis method in this paper, the calibration system error was corrected, and the seeker zero error was reduced to within 1 mrad from 2.5 mrad before the calibration. The conclusions of this paper provides an analytical method for the precision requirement of the structure installation in the direct writing laser seeker calibration system, and thus improves the angular measurement accuracy of the laser seeker after calibration.