Abstract: Dormancy is a phenomenon that plant grow slowly or reach a temporary pause. It occurs when plants are resisting to or adapting to environment stress. The time of effective low temperatures required for dormancy breaking is called the chilling requirement. In this study, different chilling estimating models as long as their application effects are summarized and analyzed. Currently, application of Utah model has a higher frequency and better effect. Dynamic model is considered to be most perfect in theory and has the widest application range. But it has not yet been popularized, especially in China. The main object for chilling estimating models is dormant bud while there is few report on the other dormant organs (bulbs and seeds etc.). Compared with other horticultural crops such as fruit trees, there is few study on the application of chilling estimating models to ornamental plants. Few plant varieties and dormant organs types have been covered in the existing studies. As the chilling estimating models are more accurate in measuring and predicting the chilling requirement during dormancy breaking compared with the chilling hours, it will have a better prospect for regional planning and introduction of ornamental plants. At the same time, exploration of the biological mechanisms involved in the accumulation of the chilling requirement, as well as optimization of the chilling estimating models for universal applications in different climate types are the problems that need to be solved in the future research.