Abstract: The Singular Cross Spectrum Analysis (SCSA) method was employed to investigate the coupling periods of air-sea/mid-low circulation interaction using 1951-1993 500hPa and the seasurface temperature(SST) in the Nortern Hemisphere. Results show tha air-sea corrlation is noticeable on the 3-7 years scale,which is similar to ENSO circle. In this sense ENSO is a strongsignal; Quasi-ten/quasi-four year periods are prominent in the mid-low interaction, and quasifour year oscillation is uniform with the ENSO circle. Studys indicate that the mid-low interactionpossesses quasi-ten year oscillation apart from being affected by ENSO.