Background: Anterior cruciate ligament (ACL) tear is a common injury in sports. Different technigues for reconstruction of this ligament have been suggested. This paper compares the knee kinematics between "single bundle" and "double bundle" ACL reconstruction with hamstring tendon in a computerized knee model. Methods: A computer-knee modle was constructed. Then "single bundle" and "double bundle" ACL reconstruction was performed. The knee stability and ligament tension were tested in 3 different settings: 1) At 30° knee flexion under isolated postero-anterior load, valgus and rotational torque was applied, 2) In weight-bearing flexion range (from extension to 70° of flexion) an anterior load of 134 Newton was applied, 3) Knee model was loaded by a non-contact pivot farce to produce ACL rupture. Results: The results showed no significant difference between "single bundle" and "double bundle" under isolated loading. The second and third model, however, showed 4 times greater tension on the ligament in "single bundle". The "single bundle" in the second technique of testing (weight bearing) showed at most 7 mm more displacement compared with "double bundle". In the third testing technique "double bundle" was stronger than "single bundle" in valgus torque resistance. The internal rotation stability was also more in "double bundle". Conclusion: Functional stability of knee model of ACL reconstruction with a "double bundle" graft is superior to a "single bundle" graft.