Objective To investigate the effect of mechanical properties of anterior cruciate ligament (ACL) on finite element simulation of knee joint. MethodsA three-dimensional finite element model of knee joint including all the main tissues was reconstructed based on medical images, and the transverse isotropic hyperelasticity of ligament was considered as well. Three groups of ACL material property parameters were acquired by fitting three different experimental stress strain curves based on the same ligament constitutive equation, to compare the influence of different ACL mechanical parameters on the kinematic and biomechanical properties of knee joint. Results Different ACL mechanical properties resulted in different displacements in knee joint. With the change of ACL mechanical properties, the stress and principal strain in ACL changed a lot, while the trend of their distributions were basically the same. Conclusions The selection of different ACL experimental stress-strain curves can influence the simulating result of the finite element analysis. More attention should be paid to the determination of ACL mechanical properties, the reconstruction and validation for the finite element model of knee joint.