Objective: To analyze the consistence of Tonnis classification and International Hip Dysplasia Institute (IHDI) classification in Developmental dysplasia of the hip (DDH) children with delayed development of femoral, and determine the reliability of IHDI classification. Methods: From January 2010 to January 2017 in Wuxi Children's Hospital Wuxi, a total of 80 cases of 6 months old to 15 months old DDH patients (88 hips) of the X-ray film, respectively, There X-ray films were evaluated by Tonnis classification and IHDI classification by 3 doctors. In order to determine the reliability of IHDI typing classification system, the Kappa method was used to analyze the differences in the same classification system of different doctors. Results: The mean kappa values of Tonnis classification system and IHDI classification system were 0.8475 and 0.9501, respectively. Weighted kappa values also showed good agreement, but IHDI showed better consistency (0.9510 vs 0.8554); in a group without femoral head ossification, IHDI showed better agreement (0.9518 vs 0.8192). Conclusion: The IHDI classification system is more consistent than the Tonnis classification, and has a better practicability for the children with delayed ossification of the femoral head.