Abstract Objective: Chronic ankle instability is one of the most common sports injuries in the clinic, and relevant animal models have been established to study the injury mechanism and rehabilitation assessment, but there is a lack of in-depth studies on gait parameters in animal models. Methods:Thirty C57BL/6J male mice were randomly divided into two groups, i.e., the control group and the injury group. In the control group, the ankle joint was sham-operated, and in the injured group, the anterior talofibular ligament and the calcaneofibular ligament of the left ankle joint were dissected. Gait parameters were analyzed in each group using TreadScan passive gait analyzer. Results:Compared to the control group, the mean standing time as well as the percentage of standing time increased by 28.43% (p<0.05) and 23.07% (p<0.05) in the injury group, whereas the mean swing time and the percentage of swing time were shortened by 50.63% (p<0.001) and 19.75% (p<0.01), respectively. The mean braking time and mean stride time of the injury group were also shortened by 18.37% (p<0.01) and 37.86% (p<0.001), respectively. Step length and anterior-posterior step width were shortened by 36.96%, 13.66% and 8.10% respectively in the injury group, in addition to this, total and instantaneous speed of movement decreased by 8.05% and 11.12% respectively in the injury group, while stride frequency increased by 51.41% instead. Mean footprint area and mean maximum standing area decreased by 8.8% and 13.24% in the injury group, and foot pressure decreased by only 3%. By further analyzing the distribution of plantar pressure, we found that the distribution of plantar pressure in the injury group was not uniform, and the decrease of plantar pressure in the hindfoot was more obvious, especially in the right posterior quadrant by 13.92%. Conclusion:Based on the Treadscan gait analyzer, we found that mice with chronic ankle instability adopt a more conservative walking pattern during exercise, by reducing the amount and amplitude of movement in order to improve the coordination and stability of walking. This study is hoped to provide a reference for the study of the mechanism of chronic ankle instability as well as the screening and evaluation of drugs. Keywords: ankle arthritis; gait analysis; ankle instability; gait compensation