After the mature stage of the ENSO events in the boreal winter, SST and latent heat flux anomalies over the tropical Atlantic during the following spring show large amplitude north of the equator but small one south of the equator. The linear decomposition analyses of the latent heat flux anomalies indicate that the contribution from wind speed anomaly shows an equatorial antisymmetric structure with same magnitude but opposite polarity between north and south of the equator, while the contribution from anomalous air-sea humidity difference counters to that from wind speed anomaly south of the equator. These results suggest an important role of anomalous air-sea humidity difference on forming latent heat flux anomaly and significantly modifies the conventional view of wind speed as the dominant effect in ENSO-induced tropical Atlantic SST changes.