Litchi is a typical subtropical evergreen fruit tree, which likes high temperature, high humidity and sunshine. Hejiang County has favorable influence: the northern part of Sichuan Province is blocked by Daba Mountain range, and it is less affected by the cold air from the south. Hejiang county is located in the subtropical monsoon climate zone, with sufficient light and heat and abundant precipitation in summer; Located in the valley along the Yangtze River, Chishui and Xishui, the terrain is low, the influence of winter wind is small, the frost period is short or even non-existent, and the frost harm is small; Hejiang county has high annual temperature, long growing period, large temperature difference between day and night, and good litchi quality. Hejiang litchi has the highest latitude in the world, the latest maturity, the best quality and the highest market price. .