Objective To evaluate the effect of EZ extraction screws device on screwing out the reduced screws，broken screws, skidded screws in biomechanical test and clinical application. Method 4 femurs, tibias, radius, ulnas of 4 fresh skeleton specimen were divided into two big groups randomly as Group A and Group B1, B2 and B3: In Group A the screws were taken out by screwdriver; In Group B, the screws were clamped in medulla cavity filled with the bone cement,;B1 was the group of measuring skidded screws with the biggest torsion; B2 was the group of measuring skidded screws with the biggest torsion by one handle; B3 was by two handles. Four mechanics test models were made, and the clamping screws were divided into two types of 4.5 mm and 3.5 mm each for 60. The experiment specimen were tested on the universal testing machines with exerting 2 kN axial loading, and surveyed the greatest torque, the torsion angle and the power loss as well as the efficiency when drawing out. The empirical datum after statistics processing were compared among the groups. And EZ was also used for 12 example patients in the preliminary clinical practice. ResultsGroup A showed the biggest torque as 1.42～1.96 N·m for drawing out; Group B1 as 2.87～3.27 N·m; Group B2 as 3.06～4.83 N·m; Group B3 as 4.12～8.36 N·m. The significant difference （P<0.05）was found in each group. The average value of torsion angle in each corresponding group is 1.59°,0.77°,0.28° and 0.16°, respectively with the obvious difference （P<0.05）; The average value of power loss in each group is 12, 21, 32 and 45J respectively; and the power (mechanical efficiency) in each corresponding group is 0.20, 0.35, 0.53 and 0.75 T/s, respectively, which also showed the obvious difference （P<0.05）. EZ used in 12 cases were successfully screwed out with all the broken screws and maintained the integrity of the bone without any postoperative complications. Conclusions EZ extraction screw device has sufficient torsional strength and stiffness with enough clamping force, and could pull out stably and reliably, which is an ideal tool for the stub screws, crooked screws and slipped screws in skeleton.