Abstract: By use of annual numbers of the Tropical Cyclone (TC) in 48 years (1949—1996) and monthly mean characteristic parameters of the South Asia High (SAH) in 40 years (1958—1997), the features of interannual and interdecadal variations as well as the period and period energy of the annual TC numbers are analyzed. Furthermore, the relationships between the annual TC numbers and the characteristic parameters of SAH are depicted, and the features of the SAH circulation and the 100 hPa height field in prior time in TC abnormal years are also composed and discussed. The results show that the TC numbers in Northwest Pacific have obvious interannual and interdecadal variations, and that the SAH in prior time has a certain influence on the TC frequency in a year. When the center of the SAH goes more westward and northward, and its center intensity is weaker, the TC numbers in the year would be more, and vice versa.