A three dimensional (3D) Finite Element (FE) human knee joint model developed from magnetic resonance images (MRI) has been validated with the sets of experimental results in a normalized scale. The performance of the 3D FE knee joint model has been tested, simulating a physical experiment. The experiment provided the direct measurement of Anterior Cruciate Ligament (ACL) strains due to the forces of Quadricep Muscle Force (QMF) followed by Ground Reaction Force (GRF) at low knee flexion. Accurate and precise anatomy has been obtained from segmented MRI images. The ACL strain subject to the loading was calculated and analyzed compared with the measured data from the experimental tests. The study shows that the pre-activated ACL strain, which is measured before the application of GRF, increased nonlinearly with increasing QMF before landing. However, the total ACL strain, which is measured after both QMF and GRF applied, reaches out to the limited constant value (6%) instead of crossing the ACL failure value. These results suggest that the forces generated from QMF and GRF at low flexion may not bring ACL to a failure level as presented in the experimental tests. The results of the FE model fall into the standard deviations of the 22 cadaveric knees testing results, which represents the successful mechanical modeling of ACL and the surrounding structures of the human knee joint. The model may further be used to investigate the risks of the ACL injury.