Objective To explore the value of the spiral CT three-dimensional reconstruction imaging in congenital dislocationof hip(CDH) in children.Methods A total of 45 patients(59 hips) with CDH were checked-up with spiral CT and three-dimensionalreconstruction imaging before operation.The femoral neck anteversion(FNA) and the acetabular index(AI) were measured and alsocompared with the seeing in operation.Results The patients' FNA were all greater than normal,with the greatest was 90?and the smaller was 40?,the average was 42.72??12.06?.Their AI were also greater,with the average of 35.4??9.5?,the acetabulum were hypogenesis with different degreee.Conclusion The 3D CT of hip joint provides precise information of the imaging compare with the X-ray.It is a very useful technique in the FNA and AI measuring and it is also useful for the diagnosis and treatment planning of CDH.