By using the HYSPLIT_4 Model and NCAR/NCEP reanalysis data form 1948 to 2003,the interdecadal variations of the water vapor transportation paths over North China in summer(JJA) have been calculated and discussed in this paper.The results showed that the characteristics of water vapor transportation change were obvious.The dominant direction of the water vapor transportation at 850 hPa over North China in summer(JJA) from 1950 to 1970 was from south.In 1970's,the direction of the water vapor transportation became from west and it was from northwest in 1980's.In addition,there was maximum for the vertical integral of vapor fluxes from 1960 to 1964,which began to decrease from 1965.The vapor flux was less and stable since 1977.The variations of the water vapor transportation paths is related with the weaken of summer monsoon over East Asia.The character of water vapor transportation path in North China region in summer months(JJA) is very different from 1950's to 2000's.