With the one point correlation method.calculations are made for mid summer 500hPa teleconnection patterns,revealing that there exist seven in July and six in August with their centers located and their yearly intensity indices(1951～1990)calculated. The interannual and intermonthly variations are examined. It is shown that the East Asian/Pacific(EAP)and Northern American East/West(NAEW)pattern in July and the EAP and Eurasian(EU) patterns in August are closely related to mid summer monsoon rainfall in China. The weak EAP in 1991 is an important factor of the severe flooding over Jianghuai Valley of that year.