Abstract: Based on the data of NOAA sea surface temperature anomaly field, NCEP/DOE wind field, atmospheric perceptible water field data and PREC/L precipitation data from 1979 to 2017, the effects of El Niño on May precipitation of Tibet were analyzed. The results shows that during the year of El Niño, there is an anti-cyclone circulation deviation at 700 hPa in the Indo-China peninsula, which form subsidences, and there is less perceptible water in the atmosphere and less rainfall in Tibet. In the year of La Nina, a cyclone in the Indo-China peninsula occurs at 700 hPa, resulting in updrafts. The amount of perceptible water in the atmosphere is high, and precipitation in Tibet is high.

Key words: tropical SST, SEOF, precipitation, East Asian jet, El Ni$\widetilde{n}$o, Tibet