Power　performance　of　pneumatic　motor　(PM)　limits　its　application　in　compressed　air　vehicle　(CAV)　as　an　auxiliary　power.　This　study　presents　an　investigation　of　the　power　system　with　parallel　operation　mode　based　on　experiments　to　improve　the　power　performance　of　PM.　First,　the　test　bench　of　PM　in　parallel　operation　mode　is　built.　Then,　a　series　of　experiments　are　conducted　to　investigate　the　effect　of　key　parameters　on　the　power　performance,　economy　and　energy　conversion　efficiency　of　CAV.　The　interaction　among　the　key　parameters　of　the　PM　and　the　influence　of　them　on　the　power　performance　are　discussed.　Subsequently,　the　power　performance,　economy　and　energy　conversion　efficiency　of　the　PM　working　in　single　and　parallel　operation　modes　are　compared.　Experimental　results　show　that　the　maximum　power　output　of　the　PM　is　979　W,　and　the　energy　conversion　efficiency　of　PMs　1　and　2　are　6.54%　and　6.80%　when　the　PM　works　in　parallel　operation　mode.　The　parallel　operation　mode　of　PM　can　improve　the　power　performance,　economy　and　energy　conversion　efficiency　of　CAV.