Based on the yearbook of tropical cyclone data from 1983 to 2013,the NCEP/NCAR reanalysis data and the 74 circulation indexes of the former year published by the Climate Diagnostics and Prediction Division of the National Climate Center, this paper statistically analyzes the features of the TC generated in the Western Pacific as well as TCs influenced Hainan in the past thirty years and clarifies the reason of the abnormal characteristics why the tropical cyclones generating in the Western Pacific in 2013 were more than the perennial, and more TCs appeared in the autumn and affected Hainan. The results show that the anomaly of subtropical high, summer monsoon, cross-equatorial flow, sea surface temperature and Northern hemisphere polar vortex were the main reason of the more tropical cyclones in 2013. By the development of the cold high in the southern hemisphere the strengthened cross-equatorial flow made the equatorial westerly wind intensified. The convection in the Inter-Tropical Convergent Zone (ITCZ) on the south of subtropical high was active because the subtropical high was weak and located northward and the summer monsoon was strong. The sea surface temperature was higher in South China sea-Western Pacific than surrounding sea. The polar vortex was weak and westerly and meridional and zonal circulation was also weak. The cold air in the mid-latitude areas was infrequent. These all circulation conditions are conducive to the formation of tropical cyclones in Western Pacific. In additional, east-west subtropical high and higher sea surface temperature in South China sea made the TCs generating in South China sea and eastern ocean of the Philippine easy to move west to affect Hainan.