Based　on　the　off-design　models　of　compressor　and　turbine,　and　the　transient　model　of　the　packed　bed　heat　storage　unit,　a　complete　charge/discharge　cycle　of　the　adiabatic　compressed　air　energy　storage　system　with　two-stage　packed　bed　heat　storage　unit　is　simulated.　A　detailed　thermodynamic　analysis　of　systems　overall　performance　and　the　off-design　performance　of　main　components　are　carried　out.　Results　show　that　the　system　round　trip　efficiency　can　reach　62.4%.　In　the　charge　process,　the　compression　ratios　and　isentropic　efficiencies　of　two　compressors　vary　with　the　increased　air　cavern　pressure,　resulting　in　a　variable　outlet　temperature　of　packed　bed　heat　storage　unit.　In　the　discharge　process,　the　turbines　always　operate　in　off-design　condition　since　the　decreased　outlet　temperature　of　the　packed　bed　heat　storage　unit.　©　2022,　Solar　Energy　Periodical　Office　Co.,　Ltd.　All　right　reserved.