The　regular　cleaning　of　the　air　duct　of　the　central　air　conditioning　system　can　both　improve　the　indoor　air　quality　and　save　energy,　hence　it　is　very　important.　This　paper　introduces　a　type　of　robot　system　designed　to　do　the　cleaning　of　the　air　duct　and　the　four　components　of　the　robot　system　are　described　in　detail.　System　structure　and　components　configurations　of　the　robot　system　were　optimized　based　on　an　analysis　of　the　technical　principles　and　performance　parameters.　Also　in　this　paper,　a　dust　collecting　mode　called　closed　circulation　was　proposed　and　improvements　were　made　to　the　shape　of　the　brush.　Finally,　a　field　test　was　carried　out　and　comparisons　of　the　dust　and　air　velocity　in　the　air　duct　before　and　after　the　cleaning,　respectively,　were　made.　The　effects　of　the　robot　system　on　the　improvement　of　the　air　quality　and　current　organization　were　analyzed.