Objective: To evaluate knee biomechanics of patients about 12 months after anterior cruciate ligament (ACL) reconstruction during cutting and determine the abnormal biomechanical characteristics. Methods: Sixteen males about 12 months after ACL reconstruction were recruited for this study. Three-dimensional kinematic and kinetic data were collected during cutting movement. Knee joint angles and moments were calculated. Paired t-tests were used to compare the differences in knee biomechanics between the surgical leg and nonsurgical leg. Results: The peak posterior ground reaction force (surgical leg: 0.380±0.071; nonsurgical leg: 0.427±0.069, P = 0.003) and vertical ground reaction force (surgical leg: 1.996±0.202, nonsurgical leg: 2.110±0.182, P = 0.001) were significantly smaller in the surgical leg than in the nonsurgical leg. When compared with the uninjured leg, the surgical leg demonstrated a smaller knee flexion angle (surgical leg: 38.3°± 7.4°; nonsurgical leg: 42.8°± 7.9°, P < 0.001) and larger external rotation angle (surgical leg: 10.3°± 2.4°; nonsurgical leg: 7.7°± 2.1°, P = 0.008). The surgical leg also demonstrated a smaller peak knee extension moment (surgical leg: 0.092 ± 0.031; nonsurgical leg: 0.133 ± 0.024, P < 0.001) and peak knee external rotation moment (surgical leg: 0.005 ± 0.004; nonsurgical leg: 0.008 ± 0.004, P = 0.015) when compared with the nonsurgical leg. Conclusion: The individuals with ACL reconstruction mainly showed asymmetrical movements in the sagittal and horizontal planes. The surgical leg demonstrated a smaller peak knee flexion angle, knee extension moment, and knee external rotation moment, with greater knee external rotation angle.