The　structure　and　principle　of　two-stage　evaporative　cooling　system　are　discussed.　Its　mathematics　model　is　built　to　simulate　working　process.　With　the　sychrometric　chart,　the　air　handling　process　is　analyzed.　In　order　to　investigate　the　performance　of　this　new　kind　of　air　conditioner,　effects　influenced　the　performance　of　the　filler　are　fully　discussed.　Experimental　research　is　finished　to　discover　the　relations　and　the　best　disposition　among　various　parameters.　The　experiment　data　corresponding　to　different　weather　conditions　are　given　at　the　same　time.