Abstract:Based on the global reanalysis data of Shilin from 2010 to 2019 and through the backward trajectory of HYSPLIT model, the water vapor sources in different seasons and heights were tracked and analyzed. Results show that:there are differences in water vapor source and water vapor migration path in four seasons in Shilin. In spring, the water vapor mainly comes from Eurasia and northern Africa affected by upper westerlies; in summer, it mainly comes from Bay of Bengal, South China Sea and western Pacific; in autumn, it mainly comes from Bay of Bengal, South China Sea and western Pacific; in winter, it mainly comes from the upper westerlies and bay of Bengal in Eurasia and northern Africa. There are five water vapor channels in Shilin, including Arabian Sea and bay of Bengal South China Sea, western Pacific, Eurasian African continent and local water vapor channels. There are great differences in water vapor transport channels and water vapor contribution rates at different altitudes in spring, summer, autumn and winter.