In the present study, the connection between the Arctic Oscillation (AO) in May and the following summer (June to September) western North Pacific tropical cyclone genesis frequency is investigated based on NCEP/NCAR reanalysis data and tropical cyclone data from China Meteorological Administration for the period 1950–2018. A statistically significant positive correlation is found between the late spring AO and summer tropical cyclone genesis frequency. The diagnosis results show that the low-level relative vorticity, high-level divergence, vertical wind shear and the mid-low level relative humidity are all beneficial for the genesis of the western North Pacific tropical cyclones during the positive AO years. Moreover, the western Pacific subtropical high shifts eastward and northward and tends to be much weaker. On the contrary, during the negative AO years, the tropical cyclone formation is reduced because of the strengthened western Pacific subtropical high combined with an anticyclonic vorticity in the lower troposphere. The possible mechanism involved the variations of the storm track in the North Pacific. It is showed that during the positive (negative) AO years the storm track is moving northward (southward) and there is a cyclonic (an anticyclonic) vorticity anomaly in the lower troposphere in the western North Pacific in the subsequent summer through the interaction between the synoptic-scale eddies and low-frequency mean flow. The resulting anomalous local Hadley circulation could lead to the change of the western Pacific subtropical high and further contribute to the western North Pacific tropical cyclogenesis.