Bones are important natural materials which compose the skeleton of the animals. The basic and fundamental function of bone is mechanical - to provide a frame to keep the body supported and moved, to protect internal organs, while they also serve with other important biological functions, such as blood production, mineral storage, etc. Such multifunctionality makes bone with a very complex hierarchical structure, while the millions of years' evolution makes bone have outstanding characteristics, in mechanical aspect of view, bone has a high strength and high toughness while keeping lightweight. These natural exceptional mechanical properties of bone are much better than that of the conventional artificial materials are inspiring the materials engineering community to design the novel biomimetic materials. However, on the other hand, as a natural material which lies in the body of organism, numbers of diseases infects bones and severely weakens their instinct properties, therefore, to cure the patients and recover basic functions of bone, many researches are needed to find the biological substitute of bone.