A method for determining an axial direction of a bore of a bone fixator includes the following steps: obtaining X-ray images of the bore, calculating perpendicular bisectors, determining spatial planes, and obtaining the axial direction of the bore. After X-ray images of the bore are taken from two X-ray source positions, two overlapping images of the bore are obtained for calculating two perpendicular bisectors therein respectively. Each perpendicular bisector and its corresponding X-ray source position define one spatial plane. The intersection of the two spatial planes defines the axial direction of the bore. Now that the axial direction of the bore can be derived from only two X-ray images of the bore taken during an orthopedic surgery, radiation exposure of the patient and of the medical personnel involved can be significantly reduced.