To investigate and compare the effect of self-design three dimension L steel plate(TDLP)and other internal fixation devices on unstable intertrochanteric fracture of femur.Method The two-part,three-part and four -part trochanteric fractures of feumr have been made by using12fresh cadaver femur samples.Six strain patches have been sticked along the medical and lateral cortices of femur.Measure strain of proximal femur and com-pression,bending and twisting under different condition.Then the femur fractures have been fixed by using TDLP,Gamma nail,Richards nail and SHS nail,respectively,And their experimental results and biomechanical functions have been compared systematically.Results Using TDLP interfixation to cure intertrochanteric fracture of femur has the similar strength rigidity as compared with Gamma nai.and the standard values(P>0.05).The TDLP offered more distinct biomechanical advantage than the Richards nail and SHS nail,there exist obvious differences(P<0.05).72cases of unstable intertrochanteric fracture of femur have been treated by self-design TDLP since1994,with the average patient age63.5and average followed-up period32months.X-ray photos showed fracture headings were excellent good and satisfactory funciton of the limbs were recovered.No slow u-nion of fracture,coxa vara deformity and rotary displacement have happened.Conclusion TDLP is more ideal in-ternal fixation object in the treatment for intertrochanteric fracture of femur.