Abstract: Objective To evaluated the mechanical properties, biodegradation and biocompatibility of the Second Absorbable Complex Enhancement Bolt by animal experiment. Methods Based on the Beagle dog model for fracture of femur in 12 weeks，the bolt's bending strength, and its rate of decay,and biological absorption rate (BAR) were observed, the fracture fixation，and the growth of bone trabe-cula and bony callus were determined by Using X ray, microscope and electron microscope，and the Second Absorbable Complex Enhancement Bolt was compared with the First one at bone formation in experimental animal. Results The bending strength of the Second Absorbable Complex Enhancement Bolt was stronger than the First one in the second, fourth, eighth, twelfth week，and its rate of decay was lower than the First one. Two Bolt's bending strength decreased fast in the forth eight weeks. After that time, the decay was stabilization, and its profited the union of fracture and remodeling. At the same time，Two Bolt's biological absorption rate had no difference in statistical significance. Compared with the first bolt，the second one was earlier to promote necrotic tissue, fibroplasias，thready and osseous callus formation, and the result of X ray was hinted that bone fracture was henosised earlier. Conclusion The Second Absorbable Complex Enhancement Bolt could satisfied the need of the mechanical strength for bone fracture ’s internal fixation materials, and profit the thready and osseous callus formation.

Key words: Second Absorbable Complex Enhancement Bolt, Mechanical properties, Biodegradation;Biocompatibility