Theory　analysis　of　performance　of　two-stage　evaporative　cooling　air　conditioner　are　presented.　When　the　two-stage　evaporative　cooling　air　conditioner＇s　material　and　configuration　are　decided,　the　main　factors　affecting　the　performance　of　the　direct　evaporative　cooling　air　conditioner　are:　relative　humidity,　dry-bulb　temperature　of　inlet　air,　face　velocity　of　the　filler,　spray　density　of　water.　Its　mathematics　model　is　built　to　simulate　working　process.　In　order　to　investigate　the　performance　of　this　new　kind　of　air　conditioner,　effects　influenced　the　performance　of　the　filler　are　fully　discussed.　Data　corresponding　to　different　weather　conditions　are　given　at　the　same　time.　The　composite　fiber　filler　which　we　use　has　big　specific　surface　area　and　resistance.　The　effect　of　cooling　and　humidifying　is　better.　When　the　outdoor　temperature　is　above　25　degrees　C,　relative　humidity(phi)　is　less　than　50%,　the　drop　of　temperature　can　reach　more　than　6.3　degrees　C.　The　cooling　efficiency　is　around　80%.　The　direct　evaporative　cooling　air　conditioner　not　only　has　good　effect　in　hot　and　dry　area　but　also　can　improve　the　air　quality　by　replacing　the　traditional　air　conditioning.　It　can　also　save　the　preliminary　investment　and　working　expense.　The　cost　saving　of　preliminary　investment　is　40%　and　the　working　expense　is　70%.　And　it　uses　water　as　the　refrigerant　to　replace　the　Freon,　so　this　air　conditioner　can　be　called　green　air　conditioner　because　it　won＇t　pollute　the　environment.　This　can　be　widely　applied　in　the　factories,　restaurants,　show　business,　gymnasium　and　other　business　situations.　From　the　data　measured,　when　the　relative　humidity　exceeds　80%,　the　drop　of　temperature　is　less　than　3.6　degrees　C,　so　it　is　not　applicable　in　the　south　of　China　with　large　humidity　in　summer.