Defined are three indices about western Pacific subtropical high(WPSH),i.e.,the WPSH ridge index,area index and western extension index.On the basis of the indices,the interannual relations between equatorial eastern Pacific SSTA and WPSH are studied,and further discussion reveals the influence of equatorial eastern Pacific spring SSTA on the seasonal change of WPSH.Results show that the equatorial eastern Pacific spring SSTA is closely connected with the strength and position of summer WPSH on interannual and seasonal scales.Related to the warm(cold) spring SSTA in the equatorial eastern Pacific,the WPSH from spring to summer lies to the south(north) of its mean,the west(east) of its normal,and is slightly intensified(weakened) with insignificant(noticeable) northward shift in June and slow(fast) southward retreat in Autumn.