The purpose of this study was to reduce the airborne noise emitted from the package air-conditioner(PAC) therefore, the optimim design melthods of the fans and the flow-paths were investigated experimentally through the anlaysis of the nose problems caused by the conventional PAC system, and the fan performance tests and the systme resistance measurements of the parts which belong to the flow-paths of the PACwere used to study these noise problems. As a results, through the optimized flow-paths of the new PAC system with the lowset system resistance, and by adjusting and matching the operating point of each fan to each PAC system, the airborne noise reductions from the new indoor PAC and the outdoor one were achieved upto 5.5 dBA and 6.6 dBA respectively in overall noise level as compared with the conventional PAC system.