Ceiling-mounted air conditioner

The present invention discloses a ceiling-mounted air-conditioner. It includes: machine shell placed on the ceiling board, air supply fan and motor mounted in the centre of top portion of machine shell, heat exchanger which is made into quadrilateral form and is used for surrounding the air supply fan and fixing support frame for fixing the heat exchanger on the top of machine shell. It also includes noise-reducing device, i.e. guide plates which are mounted on the inner sides of all the fixing support frames respectively and inclined toward the rotation direction of air supply fan. By the action of guide plates the sucked air can be smoothly flowed toward the heat exchanger, so that the noise can be greatly reduced.