Objective By comparing with the traditional X-ray template measurement method, to explore the accuracy of artificial intelligence preoperative planning system (AI-HIP) to predict the type of prosthesis and guide the placement of prosthesis before total hip arthroplasty (THA) in adult patients with developmental dysplasia of the hip (DDH). Methods Patients with DDH scheduled for initial THA between August 2020 and August 2022 were enrolled as study object, of which 28 cases (28 hips) met the selection criteria were enrolled in the study. Among them, there were 10 males and 18 females, aged from 34 to 77 years, with an average of 59.3 years. There were 12 cases of the left DDH and 16 cases of the right DDH. According to DDH classification, there were 10 cases of Crowe type Ⅰ, 8 cases of type Ⅱ, 5 cases of type Ⅲ, and 5 cases of type Ⅳ. According to Association Research Circulation Osseous (ARCO) staging of osteonecrosis of the femoral head, 13 cases were in stage Ⅲ and 15 cases in stage Ⅳ. The disease duration was 2.5-23.0 years (mean, 8.6 years). The limb length discrepancy (LLD) was 11.0 (8.0, 17.5) mm. Before operation, the prosthesis types of all patients were predicted by AI-HIP system and X-ray template measurement method, respectively. And the preoperative results were compared with the actual prosthesis type during operation in order to estimate the accuracy of the AI-HIP system. Then, the differences in the acetabular abduction angle, acetabular anteversion angle, femoral neck osteotomy position, tip-shoulder distance, and LLD were compared between preoperative planned measurements by AI-HIP system and actual measurement results after operation, in order to investigate the ability of AI-HIP system to evaluate the placement position of prosthesis. Results The types of acetabular and femoral prostheses predicted based on AI-HIP system before operation were consistent with the actual prostheses in 23 cases (82.1%) and 24 cases (85.7%), respectively. The types of acetabular and femoral prostheses predicted based on X-ray template measurement before operation were consistent with the actual prostheses in 16 cases (57.1%) and 17 cases (60.7%), respectively. There were significant differences between AI-HIP system and X-ray template measurement (P<0.05). There was no significant difference in acetabular abduction angle, acetabular anteversion angle, femoral neck osteotomy position, and tip-shoulder distance between AI-HIP system and actual measurement after operation (P>0.05). LLD after operation was significantly lower than that before operation (P<0.05). There was no significant difference between the LLD predicted based on AI-HIP system and the actual measurement after operation (P>0.05). Conclusion Compared with the traditional X-ray template measurement method, the preoperative planning of AI-HIP system has better accuracy and repeatability in predicting the prosthesis type. It has a certain reference for the prosthesis placement of adult DDH.