Objective：This study was aimed to observe and quantify the continuous changes in dental movement and trabecular microstructure in both tension and pressure zones of rats under orthodontic force using the in vivo micro-computed tomography（Micro-CT）scanning. Methods：A 50 g orthodontic force was applied to the left maxillary first molar of five 8-week-old male SD rats. The rats were scanned in vivo at different time points using Micro-CT. The distance of orthodontic tooth movement was calculated in a unified spatial coordinate system. Additionally，trabecular micro-morphological and mechanical property-related parameters in the tension and pressure zones of the moving teeth were measured and statistically analyzed. Results：There was significant displacement of the rat molars within the first 0-3 days，with a decrease in movement rate between 3 and 14 days，followed by an increase in rate between 21 and 28 days（P ＜ 0.001）. Multiple trabecular parameters in both tension and pressure zones showed turning points at 7 days and 14 days，respectively. Specifically，the values of bone volume fraction（BV/TV）and trabecular thickness（Tb.Th）were first decreased and then increased，while those of total porosity volume[Po.V（tot）]，structure model index（SMI），trabecular separation（Tb.Sp），and fractal dimension（FD）exhibited the opposite trend. During the early stage of tooth movement，the slope of increase in trabecular parameters was greater in the tension zone compared with the pressure zone. In the later stage of tooth movement，there were significant differences in the values of BV/TV，Po.V（tot），SMI，and Tb.Sp between the tension and pressure zones（P all ＜ 0.05）. Conclusion： Orthodontic tooth movement in rats occurs in three stages. There are differences in trabecular microstructure remodeling between tension and pressure zones，with bone mass and bone quality both decreasing first and then increasing，reaching their lowest points around 7 days and 14 days，respectively. The active phase of bone resorption in the tension zone occurs early，and bone formation in the alveolar bone of the tension zone lags behind bone resorption in the pressure zone.