The climate warming has expanded the winter wheat planting region toward north and west where the spring wheat was traditionally planted in north China. In this paper,meteorological data from 28 stations in spring wheat planting region during 1980 - 2012 were used to analyze the cause for changes in cropping structure from spring wheat to winter wheat and its risk of freeze injury in north China. The results show that,in the past 33 years,the annual average air and surface temperature (Tave,Ts - ave) have significantly increased by 1. 3,1. 98℃,respectively,and mean annual minimum air and surface temperature (Tmin,Ts - min) have significantly increased by 1. 58 and 2. 83 ℃,respectively. The effective temperature accumulated during winter wheat growing season increased 340 ℃d. The number of days and accumulation of cold in each year with minimum air temperature and surface temperature below 0 ℃ were decreased significantly by 4. 6,5. 6 d /10a and 57,233. 8 ℃d /10a, respectively. The number of days and accumulation of cold in each year with minimum surface temperature below - 18 ℃ were decreased significantly by 6. 7 d /10a and 143. 5 ℃d /10a,respectively. The mean minimum surface temperature in January has significantly increased by 2. 54 ℃. The changes in these parameters have supported the expansions of winter wheat planting region toward north and west. However,as the critical parameters of overwintering for winter wheat,the average air temperature,the minimum air temperature and average surface temperature in January have not increased significantly. The number of days and the accumulated temperature in each year with minimum surface temperature below - 18 ℃ were increased from approximately 13 days and 1200 ℃d in 1997 to 20 days and 3500 ℃d in 2012. There is much uncertainty as to the range of region suitable for winter wheat planting.