1. A navigation-training apparatus for image-guided orthopedic surgery comprising: a navigation-training model, which comprises: a base, a holding device for fixing a surgical practice model bone to said base in a predetermined position, and a support mounted on said base separate and independent from the surgical practice model bone, said support configured to secure a patient tracker in a predetermined and constant orientation relative to the holding device to maintain that a constant orientation and relative position between the patient tracker and the surgical practice model bone is always constant each time a patient tracker and a surgical model bone are placed on the navigation-training model; a navigation system for storing a plurality of pre-captured images of the surgical practice model bone and having a monitor screen; and at least one surgical tool attached with a tool tracker communicated with the navigation system, wherein the monitor screen is configured to display the pre-captured images of the surgical practice model bone during a navigation-training, the surgical tool is configured to move in relative to a desired position in the surgical practice model bone during a navigation-training, and the monitor screen is further configured to show a tracked position of the surgical tool based at least on the tool tracker over the displayed images with respect to a coordinate frame provided by the patient tracker in a 3D coordinate system during a navigation-training, so as to make the surgical tool to be accurately positioned in said desired position in the surgical practice model bone.