Abstract: The tropical middle-eastern Pacific temperature correlation index (TPTI) is established based on the area average of the correlation degree. TPTI shows much similarty with traditional indices, which also denotes the correlation actions between the tropical middle-eastern Pacific and other global areas. Besides, the year in which TPTI is higher corresponds usually to the strong El NiNo or La NiNa signal, and the reason might be that temperature synchronization area in the tropical middle eastern Pacific is lager, and the action between tropical the middle eastern Pacific and other global areas is stronger. That is to say, strong El NiNo and La NiNa years themselves might cover strong and weak action situations. The research of relation between TPTI and China summer precipitation shows that correlation coefficient between the summer TPTI and the first EOF mode of China summer precipitation field (1966-2005) is -0.28, and the correlation index for the spring TPTI and the summer precipitation is -0.34. Furthermore, the circumfluence background of hight TPTI is quite different from that of low TPTI, which is to say that TPTI might be used in the prediction of China summer precipitation and, a new effective way for the climate signal definition based on the correlation degree of network is thus proposed.