The invention discloses a method and system for preparing an artificial bone. The method comprises the steps that medical image data of a patient's bone injured part is acquired; an original bone model diagram of the patient's bone injured part is obtained according to the medial image data, image processing is carried out to the original bone model diagram, surface grid intersection points of the original bone model diagram are extracted, the surface grid intersection points and embedded free points are connected into lines, a micro-structural diagram is formed according to the lines, and a three-dimensional porous model diagram is established; and the three-dimensional porous artificial bone is then prepared according to the three-dimensional porous model diagram. The three-dimensional porous model diagram is established according to the acquired medical image data of the patient's bone injured part and then the three-dimensional porous artificial bone is prepared. The artificial bone prepared by the technical scheme has a three-dimensional porous structure; individualization and light-weight features are embodied; and the porous structure is suitable for ingrowth of tissues or bones and has high biocompatibility.