This paper discusses the modulation effect of Quasi-biweekly oscillation of cross-equatorial flow on typhoon tracks over the Western North Pacific by using the tropical cyclones (TCs) data from the American Joint Typhoon Warning Center (JTWC) and NCEP/NCAR reanalysis wind data.The typhoon tracks are divided into seven types and the evolution of low-frequency circulation in the period of the atmospheric quasi-biweekly oscillation(QBWO) is synthetically analyzed through the methods of lead and lag regression.The results show that the meridional wind and cross-equatorial flow at 925 hPa bear the characteristics of periodic oscillations of 10 to 20 days and it is useful in forecasting the typhoon tracks over Northwest Pacific.In the equatorial region of North Pacific,the low-frequency cross-equatorial flow and meridional wind can influence the low-frequency cyclone and anticyclone and modulate the typhoon tracks by regulating the position and strength of intertropical convergence zone(ITCZ).The component of the strong northward low-frequency cross-equatorial flow is beneficial for the low-frequency cyclone,and makes the ITCZ move northward.Typhoons can move along the zone of the ITCZ.The component of weak northward low-frequency flow or of southward low-frequency flow goes against the movement of typhoons.