Compressed　air　energy　storage　system　has　the　advantages　of　high　reliability,　low　cost,　flexible　layout,　and　negligible　environmental　impact.　Meanwhile,　the　low　efficiency　of　compressed　air　energy　storage　system　is　a　key　obstacle　currently　faced　by　researchers　all　around　the　world.　Compressor　and　expander　are　the　key　components　of　compressed　air　energy　storage　system;　thus,　their　efficiency　directly　affects　the　compressed　air　energy　storage　system　efficiency.　In　order　to　improve　the　economic　performance　of　compressed　air　energy　storage　system,　this　study　proposes　an　expander/compressor　integration　based　on　pneumatic　motor.　The　overall　performance　of　the　compressor　under　dynamic　conditions,　which　are　represented　by　the　pressure　change　of　the　air　tank　and　the　load　fluctuation,　is　investigated　through　experiments.　The　effect　of　torque,　air　tank　pressure,　mass　flow　rate,　and　rotating　speed　on　compressor　power　consumption　and　energy　conversion　efficiency　are　studied.　The　experimental　results　show　that　the　power　consumed　by　the　compressor　increases　with　the　increasing　of　torque,　air　tank　pressure,　mass　flow　rate,　and　rotating　speed.　When　the　rotation　speed　is　2700　r/min　and　the　torque　is　4　N·m,　the　work　consumed　by　the　compressor　reaches　the　maximum　value　of　approximately　1095　W.　The　maximum　energy　efficiency　value　of　η1,　η2,　η3,　and　η4　are　approximately　73.7%,　90%,　56.8%,　and　52%,　respectively.　©　2023　Author(s).