Abstract: Objective: To establish the ideal animal model for the study of Perthes disease.Methods: Twenty healthy young dogs were randomily divided into two groups.Dogs in one group were injected into muscle with methylprednisolone twice a week for 2 moths.Dogs in other groups were frozen by liquid nitrogen.Xray,MRI,ECT and histology examination were made periodically after experiment to evaluate osteonecrosis.Results: Necrosis of the femoral head in 4th and 8th week was confirmed in two experiment groups.The success rates were 40.0% in 4th week and 75.0% in 8th week with the methylprednisolone group,while in the liquid nitrogen group,the success rates were 90.0% in 4th week and 100.0% in 8th week.Conclusions: The model of Perthes disease could be built up by steroid-injection or liquid nitrogen in young dogs,but not all the dogs model can be built by steroid-injection.The animal model of Perthes disease with liquid nitrogen in young dogs can be established.