Hunan has a continental subtropical monsoon humid climate. The province is 400 kilometers away from the sea, which is closely related to the influence of East Asian monsoon circulation. Climate has three characteristics: first, light, heat and water resources are abundant, and their high values are basically synchronous. From April to June in Hunan, the total radiation accounts for 70-76% of the total radiation, while the precipitation accounts for 68-84% of the total precipitation. Second, the climate changes greatly during and between years. It is hot in Leng Xia in winter, changeable in spring, sudden drop in autumn, rainy in spring and summer, and drought in autumn and winter. The climate changes greatly from year to year. The regional difference between the maximum value and the minimum value is 1.29 times larger than the average value, and the difference between the year with the most rainfall and the youngest year is 1.460 mm, almost three times that of the youngest year. Third, the most obvious vertical climate change zone is the mountainous area surrounded by mountains on three sides. Especially in the mountainous area of southern Hunan. The annual sunshine hours in Hunan are 1.300- 1.800 hours, with Dongting Lake being the most and Yueyang being 1.840 hours. Hunan is rich in heat. The annual temperature is relatively high, and the annual average temperature is between 16- 18℃. In winter, Hunan is controlled by the winter wind, but it is surrounded by mountains in the southeast and open to the north, which is conducive to the long-term drive away of cold air. Therefore, the average temperature in 1 month is between 4-7℃, the frost-free period in Hunan is 260-3 10 days, and most areas are between 280-300 days. The average annual precipitation is between 1200- 1700 mm, which is abundant and one of the provinces with more rainfall in China.