[Objective] To develop an home-made visual electromagnetic navigation system and observe the effect of applying this system to assist the distal screws locking in intramedullary nail in femur models.[Methods] The testing principle of the navigation system was predicting the coordinate position of the object to be measured by testing the rate of change in the intensity of three mutually perpendicular magnetic fields. The scheme was to binding the location coil and the magnetoresistance sensor. 30 femur models were randomly divided into navigation group and general group. Each group had 15 models. The intramedullary nails with grips were inserted into femur models. The navigation group was applied the visual elcectromagnetic navigation system to assist the distal three screws locking in intramedullary nail. The general group was applied the mechanical aim device to lock the three screws. The time and one time achievement ratio of three screws locking in intramedullary nail of two groups were recorded. [Results] The time of No 1、2、3 screw locking of navigation group was （156.27±14.75）s, (230.73±17.05)s，and (306.53±20.75)s respectively. The time of No 1、2、3 screw locking of general group was （266.80±31.19）s, （318.13±32.19）s，and （408.60±27.74）s respectively. There was statistical significance difference on time between two groups.There was not statistical significance difference on one time achievement ratio between two groups. [Conclusion] The visual electromagnetic navigation has precise navigation. Compared with the mechanical aim device, it can obviously shorten the time of the distal screws locking in intramedullary nail of femur models .