According to temperature and phenological data of the latest 2 years from different altitudes of the Guifeng mountain, Macheng of Hubei Province, in combination with the previous phenology, the accumulated temperature conditions at different heights and different times for different elements are studied. The result shows that the critical temperature for ancient azaleas bloom is ≥10 ℃ stably ; and the indicators (active accumulated temperature) for full bloom are devised. Further analysis indicates that the two factors are closely related with flowering dates. Taking the above two factors as predicting factors, for the period from the end of March to the end of April, once every 5 days,seven flowering forecast formulas with high accuracy are established. The accumulated temperature indicators can be used, combined with the regression equation, to make rolling and fine forecast of ancient azaleas flowering time.