Abstract: The occurrence and evolution of spring frost in Jiangsu province follows certain laws, and it has obvious impact on the spring tea production. In this paper, we analyzed the evolution trend of spring frost during 48 years by using observation data of 35 weather stations in Jiangsu province from 1961 to 2008. Meanwhile, using factual observation data of the exploration period of Suzhou Dongting Biluochun tea from 1995 to 2008, and the observation data of Wuzhong weather observation station in the corresponding time period, adopting system analysis method, we established the model for calculating the time of tea exploration through temperature index. The results showed that, in nearly 48 years in the Jiangsu province, the average date of final frost came significantly earlier and the number of spring frost days showed a significant reduction in the trend; special night frost occurred before 1981, and late frosts appeared before 1995; the days of end frosty and spring frost were occurred with abrupt climate change in the late 1990s; climate warming accelerated the bud germination and the germination speed, but the speed of early tea picking period is not faster as the speed of early final frost. Therefore, the likelihood of frost damage in the spring tea harvest decreased gradually, and the spring frost damage on spring tea in Jiangsu province showed a reduction tendency. Activity accumulated temperature ≥10℃in February and first half of March, and the sum of average temperature between the latter half of February and the first half of March are the two key factors to determine the tea picking period. 

Key words: Spring frost, Spatial and temporal evolution, Tea, Picking time