Abstract: The asymmetric features of sea surface temperature (SST) anomalies for eastern Pacific (EP) and central Pacific (CP) ENSO events and their possible mechanisms are analyzed by using a variety of air-sea data during the period of 1961-2010. The responses of the atmospheric circulation to the two types of ENSO are also discussed. The SST anomalies exhibit asymmetry in the spatial distribution, intensity and persistence. Although the dominant mechanisms vary in both the development and decay stages for the two events, the ocean vertical advection term plays a key role in their asymmetry of both EP and CP ENSO events. The local and remote atmospheric responses both show strong asymmetric signal, which is consistent with the asymmetric distribution of SST anomalies. The asymmetric distributions of atmospheric responses in EP-ENSO are similar to those associated with EP-El Nio and the asymmetric responses in CP-ENSO are similar to those associated with CP-La Nia. The intensity of the EP-ENSO related asymmetric responses is much stronger than that of the CP-ENSO.