Abstract: In this paper, the noises resources of central air conditioning unit were summarized as following three factors being from pneumatic,mechanism and electromagnetic, and the measures for controlling noise of central air conditioning system were p roposed, including the choice of good power parts with high damp ing pad and multi2 blade axial flow blade, the design of rational sound p roof damp ing structure with metal netmask and the rational de2 sign and installation of units by using rational installation technology and sound damp ing device. The p ractice shows that the noise of central air conditioning system can be easily controlled by using the methods p roposed in this pa2 per.