Abstract:Using large-scale reanalysis files and stationary satellite cloud pictures,we analyzed respectively the lager-scale circulation backgrounds associated with tropical cyclone formations in the Western North Pacific between 1995 and 2004.And we got a conclusion that about 27.5% of tropical cyclogenesis cases in the past ten years were attributed to the Intertropical Convergence Zone(ITCZ),45.6% occured in monsoon troughs,10.1% occurred in easterly waves,10.4% occured under Tropical Upper Tropospheric Trough(TUTT),and 6.3% occurred in baroclinic disturbances.We analyzed the characters of tropical cyclones under different large-scale circulation backgrounds,such as life cycle,origion,intensity,horizontal scale,and landfall,and finally found that TCs of baroclinic disturbance category had a shorter life and was weaker than any other category of TCs.The average life cycle of the baroclinic disturbance category of tropical cyclones was 108.60 h,and the average intensity 39.250 kn,while the average of others was about 200 h and 70—80 kn respectively.1/3 of the monsoon trough category of tropical cyclones would land in China,which is of the highest possibility.The secondary was the easterly wave category.TCs of baroclinic disturbance category were of least possibility.Only those that formed in the South China Sea might land in China.