The projection of future changes in HC has been much concerned. The mid-Pliocene warm period is considered the most accessible example of a world analogous to the RCP4.5 projected warming at the end of this century, as the mean global temperatures are estimated to be 2–3℃ above pre-industrial temperatures. By performing a comparative study of the HC changes in the context of mid-Pliocene and RCP4.5, it is of vital importance to fully understand the mechanisms of the HC changes and its potential impact on regional climate as well as the uncertainties in future climate projection. In this project, we first examine the similarities and differences of mid-Pliocene HC changes in coupled model and in atmospheric model participating in PlioMIP1, and then demonstrate the dominant mechanism for the changes in HC intensity and edges in mid-Pliocene. By comparison the dominant mechanism for HC changes in mid-Pliocene with than in RCP4.5 scenario, this strengthens the idea that the mid-Pliocene could be a useful tool for understanding HC changes in the future.