This paper reviews the biomechanical effects of open and close chain exercises on knee joint after reconstruction of autologous hamstring tendon grafts. By searching and collecting the relevant literatures,it finds that in the open chain exercises,with the increase of knee flexion angle,when the quadriceps femoris contracts separately, the load of anterior cruciate ligament shows the tread of first increase and then decrease；when the hamstring contracts separately,the load of anterior cruciate ligament is gradually decreased. While in the close chain exercises,the standard squat training produces a few or no load on the anterior cruciate ligament,which can be reduced by getting the heel on the ground or increasing the trunk anteversion；compare with the both legs squat,the load peak of anterior cruciate ligament in single leg squat is greater. In the close chain leg-press,the height of the feet and the width of the support surface show no effects on the load of anterior cruciate ligament.