Objective: To compare the clinical result of treadmill training with partial body weight support(TTPBWS) and conventional physical therapy(PT) in patients with anterior cruciate ligament reconstructions. Design: Prospective randomized controlled trial. Subjects: A total of 41 patients after anterior cruciate ligament reconstructions were randomly allocated to either a treatment group or a control group. Interventions: Patients in the treatment group completed 6 months conventional physical therapy plus gait training on treadmill training with partial body weight support. Main measures: Circumference of Lower extremities, Holden classification, 10-meter-walking-test and International Knee Documentation Committee (IKDC) were compared at the 12th week and the 6th month post-operation by the same therapist. Methods: Patients who were able to walk independently with crutches after anterior cruciate ligament reconstructions were randomized to receive either treadmill training with partial body weight support (treatment group) or conventional physical therapy (control group). The Circumference of Lower extremities, Holden classification, 10-meter-walking-test and International Knee Documentation Committee (IKDC) were compared at the 12th week and 6th month post operation. The knee joint stability test was performed 6th month post operation by KT-1000. Results: Significant differences were found in Holden classification, 10-meter-time, Circumference of Lower extremities and International Knee Documentation Committee score between two groups (p<0.05) at the 12th week post operation. There was no significant difference between the two groups (p>0.05) at the 6th month post operation in most measures mentioned above except International Knee Documentation Committee score. Interestingly, we found that there was no significant difference between the treatment group at the 12th week and the control group at the 6th month when considering the Circumference of Lower extremities, Holden classification and 10-meter-walking-test(p>0.05). Conclusion: The function of a patients lower extremities after anterior cruciate ligament reconstruction can be improved and accelerated obviously by early intervention of treadmill training with partial body weight support, and without compromising the stability of the knee joints in a given follow-up period.