Objective To study the anti-twisting biomechanical properties of two new type interlocking intramedullary pin so as to provide some scientific theory for clinical application. Methods To collect four fixed damp femurs of adult cadaver , and engaged in experimental stress analysis. The anti-twisting biomechanical properties of two new type interlocking intramedullary pins fixed into the fractured shaft of femur were determined and compared them with those of Plum Blossom Nail. Results The tests of biomechanics indicated that the anti-twisting intensity and rigidity of Expansive Screw Type self-locked intramedullary pin are 2 times and 1.6 times of those of the Plum Blossom Nail, while those of Partiality Bolt Locked interlocking intramedullary pin are 1.6 times and 1.5 times compared with the Plum Blossom Nail. but only the 30% of those of integrity bone.Conclusion Both two new type interlocking intramedullary pins can gratify the demand of biomechanics. So they can serve stable or unstable fracture in the isthmus or excluding isthmus of shaft of femur.