Total hip replacement is a very effective method to cure many kinds of hip joint illnesses. About a century ago, it was first used in clinic. Since then, total hip replacement has been well developed. Hip joints sustain the most load of body, so people pay great attention to the hip prothesis' mechanics property. Especially after the finite element analysis was widely used in biomechanics investigation, the stress distribution of different designs can be easily compared with each other, and the relatively better parameters of the design could be decided. The stress distribution of different materials with the same design also can be valued. However, studies have indicated that total hip joint replacement still has some disadvantages. Loosening of the hip prothesis is still the most likely cause of the failure of surgery, and generally this is believed to stem from either mechanical failure of the fixation in response to over high density stresses, or osteolysis of the surrounding bone stock responsing to particular wear debris. Many researchers on computational studies have considered the potential for the former one, but only a few have attempted to tackle the latter. The process of osteolysis of the bone is not yet completely known. Nowadays, in order to solve the problems of loosening, investigators are trying to find different methods. Some of them are working on improving the geometry parameters and the shape of the hip prothesises, some are trying to find new suitable biomaterials, and, at the same time, the fixation methods are under deliberation.