North China is the main producing area of maize.Through analysis of relations between the phenological observations with naturally created climate change at 40 phenological observation sites during the period from 1992 to 2012,it is found that:(1)when the annual average temperature rises by 1℃,maize growing period is shortened by 3~5 days;(2)annual average temperature of 11℃is proved to be the dividing line between one-crops-per-year and two-crops-per-year planting patterns.During the observation period from 1992 to 2012,crops in northeast and northwest China had greater response to climate change than in North China Plain,indicating that stronger adaptability potentials existed in the cold climate condition.