The applicability of common defrost technologies depends on how easy it is for air source heat pumps to frost under local climate conditions. At the same time, the degree of frost formation of the air source heat pumps outdoor units are mainly affected by local climatic conditions. Therefore, this study proposes the concept of frosting degree hours, which is used to specifically characterize the impact of climatic conditions on air source heat pumps frost. In order to make the analysis and calculation of the frosting degree hours more accurate, this study carried out the collection of the actual operation data of the air source heat pumps in winter in many cities in China. Through the selection and analysis of the actual operating data, the data fitting method was used to analyze the different variables and the characteristic temperature difference between the evaporation temperature and the outdoor dry bulb temperature of systems with different power types was obtained. Finally, according to the analysis of the frosting degree hours under different characteristic temperature differences, combined with the frost characteristics of air source heat pumps of different power types in 275 cities in China, the climatic division was performed. This can provide a reference for the climate-adaptive design of air source heat pumps and the development of defrost control strategies.