Based on the low-frequency precipitation in Guizhou and the water vapor transport path in East Asia, this paper also compares and analyzes the water vapor difference and the precursory SST difference between low-frequency precipitation over many years and young years. The main conclusions are as follows :(1) The circulation pattern of "two trough and one ridge" began to form in the mid-latitude region of Eurasia in July; The circulation situation of "two trough and one ridge" was stable in August and September. The western ridge point of the subtropical high is located near 120oE, the circulation situation is gradually stable, and the precipitation in the southern region is weakened. (2) The main water vapor transport channels in Guizhou are the Bay of Bengal, the South China Sea and the Northwest Pacific Ocean, especially the water vapor transport from the Bay of Bengal through the Indo-China Peninsula and the trans-equatorial air flow from the Southern Hemisphere over the South China Sea. (3) low frequency annual precipitation frequency in the sea surface temperature (SST) over many years of the evolution of the tropical eastern Pacific anomaly largely reflects a la Nina event from the different phase of outbreak and weak period, low precipitation years frequency of juvenile sea surface temperature (SST) over the tropical eastern Pacific anomaly largely reflects the evolution of an el nino event from the different phase of outbreak and weak