Pressure can reduce the distances among atoms,thereby modifying the overall optical characteristics of molecules.In this article,the excited state behavior of perylene is carefully observed under isotropic pressure and non-complexing condition.In a steady state,absorption peak shows red shift and spectral width are broadened with pressure increasing,which is ascribed to the π-electron delocalization between molecules.In a transient state,the transition dynamics presents a wavelike tendency with pressure increasing because the shift of self-tapping exciton state is contrary to that of Y-state with pressure increasing.The results conduce to understanding the influence of inter-molecule interaction on excited state behavior with inter-molecule distance decreasing,which contributes to studying the materials under extreme condition.