Abstract: Daily mean temperature,maximum temperature,minimum temperature and minimum ground temperature based on data from Tianjin observation from 1955 to 2007 were analyzed by using the methods of linear trend,glide average and t-test.Daily mean temperature ≥0℃,≥10℃ and negative accumulated temperature≤0℃,frost-free period and change of the extreme minimum temperature≤-10℃ days were accumulated to research the response of thermal resource to climate warming and the impact of climate warming on agriculture in recent 50 years in Tianjin.The results showed that the thermal resource increased,and the abrupt of climate warming in Tianjin was in 1988,and the annual mean temperature,maximum temperature and minimum temperature of 1988-2007 were respectively increased by 1.4℃,1.6℃,1.0℃,with a maximal increase of minimum temperature.The warming amplitudes which were in the order of winter>spring>autumn>summer were 2.1℃,1.5℃,1.1℃ and 0.9℃ respectively.The temperature in winter and autumn increased significantly.Accumulated daily mean temperature ≥0℃ and ≥10℃ increased 306.5℃and 293.5℃respectively.The first frost date was delayed and the last frost date advanced,frost-free period prolonged 11.1 days.The negative accumulated temperature≤0℃ decreased 140℃.The mean days of extreme minimum temperature≤-10℃ decreased to 2.5days from 15.2days.The climate of Tianjin became warm significantly since late 1980s,thermal resources increased,the mean sowing date of winter wheat was delayed 5 days and wintering period shortened 23.5 days.Planting index increased,the thermophilic crops(cotton etc.) increased in planting area.

Key words: Climate warming, Crops, Planting structure, Tianjin