In the traditional pose detection method, the interferometer based on laser interferometry is bulky and expensive, and requires strict environmental temperature. The direct optical triangulation is limited by the aperture of the imaging lens, resulting in loss of light energy and reducing detection resolution. The oblique triangulation has serious shading phenomenon when detecting surface objects or complex surface targets, and the application range is narrow. The optical autocollimating method is applied to the field of small angles detection, but has the disadvantages of large size, low precision and complex structure. Therefore, it is of great scientific value to improve the accuracy of the pose detection system and reduce the volume of the detection system. In response to the above requirements, this paper designs an improved optical autocollimating detection system based on dual two-dimensional PSDs, which improves the accuracy and reduces the volume of the detection system. The position and angular resolution of the detection system is up to μm and μrad.