Radiocarbon (C) is a useful tracer for surface ocean circulation and mixing, which reflects air-sea CO exchange. We present radiocarbon marine reservoir ages (R) and corrections (ΔR) in Holocene inferred from 18 paired C and Th ages on fossil corals from Lanyu Island offshore eastern Taiwan. The results show large fluctuations in the ΔR value, with averages of -330 and -5 C yr for 6000–5100 yr BP and the past 150 years, respectively. The extremely young R in the mid-Holocene indicate a well-equilibrated North Equatorial Current (NEC), likely stemmed from enhanced air-sea interactions and strengthened Pacific Walker circulation. This suggests a larger E–W gradient across the Equatorial Pacific and hence La Niña-like condition, consistent with both model simulations and other paleo-proxy records. Combining the ΔR records in the northern South China Sea, the results imply an increasing influence of the NEC water on the subtropical western Pacific since the mid-Holocene.