The invention relates to a system and method for detecting the orthogonality of a precision shafting. The detection system comprises a four-dimension adjustable reticle, a television interior focusing autocollimator, and a detection platform. The four-dimension adjustable reticle is mounted on a rotating link of a pitch component of a to-be-detected precision orthogonal shafting. The detection platform is used for supporting the to-be-detected precision orthogonal shafting. The television interior focusing autocollimator is used for working with the four-dimension adjustable reticle to detect the orthogonality of the shafting through autocollimation and collimation. The four-dimension adjustable reticle is mounted on the rotating link of a shafting, the mirror surface of the reticle is adjusted to be perpendicular to the axis, the reticle center is on the axis, and the axis is simulated with the aid of the center of the reticle in the detection process rather than the center of a process hole. The limitations and defects of the prior art are overcome. After one adjustment, both the verticality and the intersection deviation can be obtained. The system and the method of the invention are based on the optical principle. The detection accuracy and efficiency are high. The method is simple. No requirement is put on the machining precision of a process hole in a bearing sleeve. The system and the method are easy to implement.