We investigate the influences of ENSO events on chlorophyll biomass in the tropical Pacific under both the historical and the RCP8.5 scenario based on the Community Earth System Model Large Ensemble (CESM-LE) project. During the historical period, our results exhibit that significant chlorophyll variations are focused on the Peruvian Upwelling (PU) region, the Equatorial Upwelling (EU) region, and the Western Pacific (WP) region in the tropical Pacific, and dominated by different mechanisms. In the future, the mean-state chlorophyll reduction limited by global warming are stronger in the eastern Pacific. Therefore, impacts of El Nino and moderate La Nina events on interannual chlorophyll anomalies are weakened in the PU and EU regions. Most of the phytoplankton bloom and chlorophyll increase happened after the occurrences of extreme La Nina events. However, in the WP region, chlorophyll concentration shows a significantly decreasing trend but its interannual variability still has a high correlation with the ENSO events, which is similar to the historical scenario. Corresponding to the chlorophyll biomass, phytoplankton dominance species shifts from diatom to small phytoplankton by the suppression of global warming. Hereafter, changes in phytoplankton community structure only occur when extreme La Nina happens compares with El Nino and moderate La Nina.