In order to realize the three-dimensional heat transfer calculating to one-dimensional, several different spherical shell models were developed. Numerical simulation was carried out based on ANSYS heat transfer analysis to analyze the heat preservation time of the model and the relative error between the model and practical insulating package. The results showed that spherical shell models can furthest reflect the heat transfer process of real insulating package when inside surface of package is close to square and the ratio of maximal size to minimal size of package is less than 2, in which the volume and the thickness of spherical shell model equals to that of the insulating package. The purpose of this research was to provide reference for optimal design of insulating package and to reduce packaging cost.