Osteoclasts and osteoblasts are not exist alone,while communicating with each other through direct contact, diffusible paracrine factors and cell-bone matrix interaction. Co-culture system of osteoblast with osteoclast,including direct co-culture and indirect co-culture. It should be according to the ratio of osteoclasts and osteoblasts under the pathology, choosing the same species. Compared with lonely culture of osteoblasts or osteoclasts,co-culture system is much closer to the microenvironment in vivo. It benefits to explain the interactions between osteoblasts and osteoclasts, exploring molecular communication in bone diseases. It was mainly used to investigate the pharmacological mechanism of herbal and western medicine in bone remodeling. Some osteoporosis drugs (such as epimedium,sanchi, fructus psoraleae, ranelate strontium) not only promoted osteoblastic bone formation, but also inhibited osteoclastic bone resorption in the system,so as to balance bone homeostasis. At the same time,it has been used to study medical physics and assess biomedical materials in recent years. Considerably,the co-cultrue system will be used to study the subchondral bone remodeling and its pharmacological mechanism of herbal and western medicine in osteoarthritis.