Abstract: In this paper, the integral regression method was used to analyse the relation between meteorological factors and phenophase of trees in spring of Beijing, The conclusions are as follows.1. The relations between meteorological factors and phenophase are very close.2. The factors which influence the phenophase of trees in spring are temperature, sunshine and precipitation in order of the intensity of their effects.3. If precipitation and sunshine are similar to those in normal years, they may be analysed in three time intervals: pre-winter, winter and spring.The effect of spring temperature on phenophese is the most important.At that time, the higher the temperature is, the earlier the phenophase occurs and vice versa. The temperature effect in pre-winter is similar to that in spring, but the intensity is smaller. The low temperature in winter also effects phenophase in spring, but the higher the temperature is, the later the phenophase, and vice versa. This shows that winter low temperature is also an essential condition for phenophase.4. Integral regression equation may be used to forecast the phenophase of the trees in spring.