The treatment of knee osteochondral injury has always been a difficult problem in the field of orthopedics, especially for young patients with large area of osteochondral defect. Among them, allogeneic bone transplantation is one of the more common treatment measures for repairing large-area cartilage damage. However, due to the consideration of clinical safety and convenience of acquisition, allogeneic frozen bone is needed. Part of the immunogenicity is removed, and the donor is partially inactivated and frozen. Only part of the chondrocytes can be preserved. Therefore, it is the same as cryopreservation in clinic Allogeneic cartilage transplantation will seriously affect the cartilage healing and clinical efficacy because of the low activity of chondrocytes. Therefore, in this study, we used tissue engineering ideas, using cryopreserved allogeneic osteochondral grafts as scaffolds and reticular micro drilling technology to simultaneously drill inactivated cartilage grafts and local bone marrow, so as to make bone marrow mesenchymal stem cells Cells (BMSCs) are released into the mesh hole surface as seed cells, and fully crawling on the "scaffold" to provide growth factors that promote cartilage healing. It simulates the three essential elements of regeneration and repair in tissue engineering technology: scaffold, seed cells and growth factors [3], and carries out allogeneic osteochondral transplantation combined with reticular micro drilling micro drilling in patients with full thickness and large area defect of knee osteochondral Fracture technique treatment, achieved good results.