Abstract: The laser angle detection system using different optical transformation characters of the beam expander in forward and converse dirction, and the angle sensitive multiply optical system of bi-directional transmission in a common aperture is combined with photoelectric precise position sensitive detector(PSD) in this system. The basic principle of high sensitive optics angle detection is analyzed, and the relation between detected angle and the signal of the position sensitive detector is given. In order to eliminate the influence of the photoelectric noise on detection resolution, the correlation detection mode is adopted in signal processing. By compressing effective band width of the system noise signal, the disturbed signal is filtered from frequency domain, and the high-resolution angl