Abstract: In this paper by using harmonic analysis the anomaly of the sea level pressure of wave number 1—3 along the latitude 60oN and 30oN in summer and winter for 1871—1975 is analyzed, and the interannual variations of the ultra-long wave (wave number 1—3) are discussed. The main results are as follows: 1) The interannual variations of wave number 1 in last hundred years showed a westward propagation in 2—3 cycles. This oscillation had a connection with the cycles of rainfall in East Asia with a period of 36 years. 2) The variations of wave numbers 2 and 3 showed an oscillation of a standing wave. The period 1871—1926 was the first stage during which the position of the trough was situated eastwards, and in the second period (1926—1975) the trough was located westwards. This change corresponded to two different climatic regims in the Northern Hemisphere, and the actives of the centers of actions showed a marked difference. This changes also resulted in the instability of the coefficent of correlation. 3) There were two stages in the sea surface temperature anomaly along 45oN latitude in the Pacific from 1860—1960, which had a connection with the change of the ultra-long wave. The variation of position of the ultra-long wave trough had a similar trend with the interannual variation of the negative anomaly of SST