Abstract: Objective：To establish an animal model of immediate tooth replantation and make further study of the behaviors of healing and absorption in the replanted tooth. Methods：The experiment was carried out on thirty 6-week-old SPF Wistar male rats(n=5). The unilateral maxillary first molar of each rat were extracted and replanted immediately, nothing was done on the other side which was the control side. The rats were randomly separated into six groups and were sacrificed on day 1, day 3, day 7, day 14, day 21 and day 28 after replantation. After sacrificing the rats, we segregated the maxillaries and scanned the samples with X-ray, so as to analyze the shaded area around the mesial root of each tooth with the Image Pro Plus software. At last tissue slices were made and stained with HE, in order to obtain histological results. Results：Radiographers displayed that the areas of root resorption expanded over time. Histologic feature showed that the number of lacuna on root surface increased with time, the width of the periodontal ligament decreased and the number of new bone like tissue increased. Conclusions：The animal model of rat tooth replantation were successfully established, and it was stable and reliable. This model reflected the healing ways and developmental resorption process of replanted tooth completely. It has been provided a good experimental model for the further research of the molecular mechanism of replanted tooth healing.