Objective To compare the three-dimensional （3D） gait characteristics of patients with medial meniscus injury of the knee before and after arthroscopic surgery. Methods Fifteen patients with medial meniscus injury and fifteen healthy subjects were included in the study. The 3D gait parameters were collected, including spatiotemporal parameters, kinematic parameters and kinetic parameters. Results (1) The preoperative walking speed and step length of the injury group were significantly lower than those of the control group. There was no significant difference in walking speed and step length after surgery between the injury group and the control group. (2) In the sagittal plane, the preoperative knee flexion-extension range of motion (ROM), the maximum flexion angle in load-bearing phase and swinging phase were significantly lower than those in the control group (P＜0.001). The maximum knee flexion in load-bearing response phase was significantly increased after surgery (P＜0.05), but the maximum flexion angle in swing phase and the knee flexion-extension ROM after surgery were still significantly lower than those of the control group (P＜0.05). In the coronal plane, the preoperative knee adduction-abduction ROM and the maximum adduction angle in gait cycle were significantly lower than those of the control group (P＜0.001). The postoperative parameters significantly increased compared with the preoperative ones (P＜0.05), but they were still significantly lower than those of the control group (P＜0.001). (3) In the sagittal plane, the postoperative first and second peaks of knee flexion moment in stance phase of the injury group increased, compared with the preoperative ones (P＞0.05), but they were still significantly lower than those of the control group (P＜0.05). In the coronal plane, the postoperative first and second peaks of knee adduction moment in stance phase of the injury group increased, compared with preoperative ones, but they were also significantly lower than those of the control group (P＜0.05). Conclusions Patients with medial meniscus injury have their own unique gait patterns, usually with stiffening gait to reduce the knee load. Arthroscopic meniscusplasty can significantly improve knee gait characteristics, but patients still cannot return to normal gait in a short period of time.