中文摘要：

通过统计合成的方法,挑选出云南5月降水的多（少）年,分别对云南5月降水多（少）年时,热带低频振荡MJO的强度和位相变化对其降水的影响研究发现,当强MJO持续位于第4~6位相时,是造成云南5月降水偏多的有利条件,其它位相的强MJO对云南5月降水的影响不大.但MJO对云南5月降水多（少）年的影响具有明显的年际变化,所以对MJO在第4~6位相时云南5月降水变异的2个典型年份作进一步研究,发现孟加拉湾的西南水汽输送的早迟以及热带MJO引发的中南半岛附近对流北传是否活跃也是影响云南5月降水多寡的重要条件.

英文摘要：

By applying the method of statistics and synthesis,the years with abundant or deficient precipitation in May in Yunnan have been picked out and studied. Variations of amplitude and phase of MJO and precipitation of May in Yunnan have been discussed. When a strong MJO continuously is located in the 4—6 phase,the precipitation of May in Yunna will be more. If the strong MJO is in other phase,the precipitation of May in Yunna will not be influenced much. After the two typical cases have been studied further,we＇ve found that if the southwest water vapor transportation in the Bay of Bengal is early or late and the transfer northward of convection acted by MJO near the Indochina Peninsula is active or inactive,the precipitation of May in Yunnan will change accordingly.