Based on the phenological data of peony and meteorological data in Heze, the correlation between first flowering dates of peony and meteorological condition is analyzed by using the statistical analysis methods, such as climatic trend rate and MannKendall abrupt change test. The results show that: (1) The first flowering dates of peony show an advanced tendency of 4.4 d/10a, and abrupt changes occurred in 1996. The first flowering date of peony is mainly concentrated in the last ten days of April from 1981 to 1996, while other mainly concentrated in the middle ten days of April in from 1997 to 2010. (2) The dates of peony flowering are mainly depended on the mean temperature of March, and the mutation nodes of first peony flowering dates and March mean temperature are consistent; the influence of February mean temperature is the second, March sunshine has certain influence on the first peony flowering dates; precipitation has no obvious influence. (3) The dates of peony flowering are predicted with the ForcTT model: the optimal beginning date is 1 February; the optimal basic temperature is 1 ℃; the average error is 1.29 days; RMSE is 1.73 days. While the basic temperature is 3 ℃, average error and RMSE are within 2 days, which also verifies that February and March temperature has great influence on the first flowering dates of peony.