The invention relates to a method for establishing a human knee joint three-dimensional simulation model in combination with CT (Computed Tomography) and MRI (Magnetic Resonance Imaging), and belongs to the technical field of medical images. The method comprises six steps of CT image acquisition, MRI image acquisition, data storage, CT two-dimensional image importing and three-dimensional model establishment, MRI two-dimensional image importing and three-dimensional model establishment, and knee joint anatomy simulation model registration and modification. The method combines the advantages of CT and MRI scanning, so that the scanning is convenient and fast, the images are clear, the dissection relation is definite, the density resolution is very high, and the scanning range is very wide. According to the method, two sets of images are registered through a three-dimensional image registration technology, three-dimensional coordinate systems of two types of images are unified by fitting point cloud contours and anatomical feature points of femurs, tibias and fibulas, and registration is performed through a registration module to obtain a double-lower-limb full-length knee joint three-dimensional digital model with structures of bones, cartilages, meniscuses, ligaments, muscle tendons and the like.