A method of locating locking holes of an intramedullary nail includes taking an X-ray image of an intramedullary nail having two locking holes； connecting centroids of the locking hole contours and an X-ray source to define locking hole vectors and axial directions of the locking holes； calculating a first included angle and normal vector perpendicular to vectors connecting the X-ray source and the locking hole contour centroids； defining a cross product of the locking hole vector and the normal vector as a vector connecting centers of the locking holes, and calculating second and third included angles with the vector connecting the locking hole centers and the vectors connecting the X-ray source to the locking hole contour centroids； and locating the locking holes according to the first, second and third included angles, vectors connecting the X-ray source to the locking hole contour centroids, and a distance between the locking holes.
