A supporting nail was designed according to the biomechanic principle and the feature of structure of bone trabecula of upper femur with an aid of guiel-pin, the upper and lower nail, passed through the compression group and tension group respectively and interlocked in the femoral head. The supihe triangular supporting frame was formed. The loading force line was re-established. Studies of experimental mechanics in vitro was performed on the cadava femur samples, which were divided randomly in 5 groups No changes of bone structure occured when the supporting nail was loaded over 2608 Newtons. The exprimental results shows the supporting nail has excellent stability of yarns or valgus motion and the axis of anti shearing dislocation.