By making use of the reanalysis monthly data(ERA-40) by ECMWF from 1961 to 2002,we calculate the vapor flux and its divergence in summer in the area of 80°-130 °E and 0°-35°N. And the temporal and spatial features of vapor flux and its divergence in summer of Yunnan are diagnosed by employing statistical methods of EOF and wavelet analysis. The result shows that,there are two vapor sources of the summer monsoon rainfall in Yunnan, while the strongest one is the southwest vapor transportation resulted from the cross equatorial flow turning and proceeding northward over the Bay of Bengal, sourcing from the Indian Ocean and the Bay of Bengal, reflecting the influence of South Asian monsoon on Yunnan. The other is the easterly jet in the south of Subtropical High, sourcing from West Pacific Ocean and South Sea, reflecting the influence of East Asian monsoon on Yunnan. And the major vapor passage of summer rainfall in Yunnan is the vapor transportation by South Asian summer monsoon. The first EOF distribution pattern of the vapor flux and its divergence by summer monsoon is roughly the anticyclone vapor transportation, which corresponds to the identical more summer rainfall in Yunnan. The second EOF distribution is roughly the cyclone vapor transportation, which corresponds to the less summer rainfall in Yunnan. The third EOF distribution is cyclone-anticyclone pattern, which may result in the summer rainfall difference from south to north in Yunnan, reflecting the summer rainfall difference from south to north in Yunnan. There is an extensive annual variability in the vapor flux of the first EOF, and 13-15 years time is its more significant period in the interdecadal variability, while 2-3 years time is its more significant period in the annual variability. And the vapor flux has been decreasing by -0.105 kg(m·s) ^-1/a since the 1960s. The vapor flux of the second EOF has been increasing by 0. 566 kg(m·s)^-1/a, and 11-15 years is its most significant period in the interdecadal variability, while its period turns to be 2-3 years since the mid 1970s. The abnormal drought and flooding years in summer have some connection with the intensity and location of the southeast vapor transportation from the Bay of Bengal and the South China Sea, and the vapor transportation in the mid-troposphere is the decisive factor.