Broken bones precise repositioning and distal hole's locking of intramedullary nails are major challenges in orthopaedic surgery. This paper proposes a novel fluoroscopy guided robot-assisted orthopaedic surgery system which called HIT-RAOS to assist the surgeons to do this work. In the system, a parallel robot is used to imitate the tact of traditional clinic treatment in long bone fracture reposition, and a serial robot is employed to guide the surgeons to accomplish the locking of intramedullary nails, which are usually used to fix the broken bones in orthopaedic surgery now. All these are going under the guiding of fluoroscopy images, provided by a precise C-Arm X-Ray machine. And a teleoperating system, a surgeon console, control software are also developed in HIT-RAOS. The major goals are to assist surgeons to reposition broken bones, to guide the surgeon locking nail, to reduce the surgeon's working time under C-Arm, to do surgery planning and teaching, to improve the accuracy of reposition and rates of successfully locking of intramedullary nails, and so on. All these are realized in this system, which already been proved in clinic body sample trials.