Objective: The current study aimed to investigate the effects of core stability training on gait improvement in patients after anterior cruciate ligament (ACL) reconstruction. Methods: A total of 74 male patients with injured anterior cruciate ligaments of the unilateral knee joint were included and randomized into group A and group B, with 37 patients in each group. Patients in group A practiced regular rehabilitation exercise following anterior cruciate ligament reconstruction. Patients in group B received additional core-stability training. Kinematic characteristics of unilateral knee joints in patients were determined six months later with the use of a 3D gait analyzer. Measures included gait space parameters (cadence, stride length, and gait speed), gait time parameters (gait cycle, stancephase and swing-phase times on the normal side and affected side), knee range of motion, and peak reaction force of joints. Knee joint function was evaluated with the use of Lysholm scores. Results: The two groups showed no significant differences in age, height, body mass index, duration of disease, smoking history, drinking history, cause of injury, and postoperative training times (all P>0.05). Compared with before treatment, cadence, stride lengths, and gait speeds of the two groups were significantly increased (P<0.05). Stride width was significantly decreased after treatment (P<0.05). After treatment, cadence, stride lengths, and gait speeds were higher in group B than in group A (all P<0.05). Stride widths in group B were shorter than in group A (P<0.05). Gait cycle, along with stancephase and swing-phase times on the normal side and affected side, in group B were better than those in group A (all P<0.05). From the first month to the sixth month after core stability training, the active knee flexion angles and passive knee flexion angles of patients in group B were higher than those in group A (all P<0.05). Peak reaction forces of the three joints (hip, knee, and ankle) of patients in group B were higher than those in group A (all P<0.05). Lysholm scores of group B were significantly higher than those of group A (P<0.05). Conclusion: Core-stability training enables patients undergoing anterior cruciate ligament reconstruction to have significantly better gait patterns and higher abilities of body balance and coordination, with good clinical significance.