A rotation detection system of three-dimensional (3D) joint surface profile based on projection light knife is designed. The rapid calibration of the detection system is realized by the use of the camera pinhole model. The center-line of the projection light knife is extracted through the optimized center of gravity algorithm, and thus the contour line of the joint surface is acquired. The oblique correction of section profile is realized by the analysis of the angle between the projection light knife plane and the rotation axis. The 3D profile data of joint surface are accurately reconstructed. The results show that the detection system possesses the advantages such as non-contact and high precision, which can be used to solve the detection problem of prosthetic joint surface profile.