Abstract: Objective To explore the application and significance of 3D printing technology in total hip replacement surgery in patients with developmental dysplasia of hip (DDH) in adults. Methods Eight cases of DDH (end-stage osteoarthritis of types of adult DDH by Crowe),including 3 males and 5 females;aged 45-63 years with a mean age of 53.6 years,were enrolled into this study.1 case of Crowe I,3 cases of Crowe Ⅱ,3 cases Crowe Ⅲ,and 1 case of Crowe Ⅳ.3D printing technology was performed before the operation to print hip model,and based on the model,we determined acetabular sclerosis and defect,defect range,oval fossa osteophytosisn,development of pre-operative planning,simulated surgical procedure,preoperative acetabular determine the true center,the size of the acetabular prosthesis model.Then the surgery operation was performed,and the intraoperative findings of the sclerosis and acetabular defect,defect range,oval fossa osteophytes hyperplasia were documented,and the acetabular grinding range and the selected size of the prosthesis,operation time and blood loss were recorded.The hip joint activities were evaluated after the surgery. Results The intraoperative findings of acetabular defect and hardened parts,defect size,intraoperative acetabular prosthesis polished range and the determined acetabular surgery center position were fully consistent with the 3D printed prosthesis model.The operative time and blood loss significantly reduced as compared with the traditional surgery.The size of the prosthesis prepared before the surgery was full fit with intraoperative prosthesis.The hip function was improved significantly after the operation with good activity. Conclusion 3D printing technology can reduce the difficulty of total hip replacement for DDH.By using this technology in total hip replacement for DDH,we can decrease the operation time and amount of bleeding,and improve the postoperative hips activity.