Based on the HYSPLIT_4,this paper tracks the water vapor transport and the source of a Northeastern Cold Vortex precipitation from July 23 to 29,2016 to anylyze the structural characteristics of this process by combining the analysis of high and low circulation and physical field.The results showed that:(1)When the Northeastern Cold Vortex is developing, the rain belt shows northeast-southwest direction, and moves eastward.(2)Impact system of high and low layer is a backward structure in vertical direction. Three fectors, jet of high and low layer, the convergence of cold and warm air,water vapor convergence over low layer,commonly causes the precipitation.(3) Water vapor are mainly from the Bay of Bengal and the South China Sea, meanwhile,a small part of the water vapor over high-layer are from the western Caspian Sea.