The large-scale circulation characteristics in summer between 1998 and 1954 were comparied.Both years happened catastropic flood in the whole Yangtze River valley since the 20th century.The results of analysis show that the second seasonal jumping northward of subtropical high over the north-west Pacific had been obviously postponed in 1954, which appeared in early August.And subtropical high was unusually southward than normal from June to July.Nevertheless,its seasonal jumping northward was advanced in 1998, which appeared in early July, and the subtropical high was further south persistently than normal from the third dekad of July to the end of August.At the same time, ITCZ of summer was notably weaker in 1998 than in 1954.But the action of blocking high of the westerly belt in Asia was very frequently in summer of the both years, especially in 1998.