The bone formation feasibility by a novel magnesium alloy device was evaluated using a canine vertical mandibular distraction osteogenesis(DO) model. Osteotomies were performed in the area where last 3 star’s teeth of left mandibular were pulled out before 3 months. Both AZ31 magnesium alloy(n ? 6) and 316 L stainless steel(n ? 6) distraction devices were implanted. The distraction osteogenesis was carried out with a latency of 5 days after mandibular osteotomy. Distraction proceeded at a rate of 0.3 mm/8 h for 7 days and followed by 4 weeks of consolidations. The evaluations were conducted by scanning electron microscopy(SEM) and histological examinations. There were osteoblasts and trabecular bones formations manifestly in both groups. There was no significant difference in the bone mineral density between the two groups. The surface of the magnesium alloy was much more cracked and uneven, resulting from the surface pitting corrosion. The crew nails were closely combined with the surrounding bone tissue. AZ31 magnesium alloy exhibited a certain degradation rate in mandibular and did not post a negative effect on the kidney and liver. The observations in magnesium alloys group is consistent with the stainless steel group. The bone formation feasibility by a novel magnesium alloy device was evaluated using a canine vertical mandibular distraction osteogenesis (DO) model. Osteotomies were performed in the area where last 3 star’s teeth of left mandibular were pulled out before 3 months. Both AZ31 magnesium alloy ( Distraction devices were implanted. The distraction osteogenesis was carried out with a latency of 5 days after mandibular osteotomy. Distraction proceeded at a rate of 0.3 mm / 8 h for 7 days and followed by 4 weeks of consolidations. The evaluations were conducted by scanning electron microscopy (SEM) and histological examinations. There were no osteoplasts and trabecular bones formations manifestly in both groups. There was no significant difference in the bone mineral density between the two groups. The surface of the magnesium alloy was much more cracked and uneven, resulting from the surface pitting corrosion. The crew nails were closely combined with the sur rounding bone tissue. AZ31 magnesium alloy showed a certain degradation rate in mandibular and did not post a negative effect on the kidney and liver. The observations in magnesium alloys group is consistent with the stainless steel group.