The invention relates to a silenced high-speed centrifugal fan which comprises a shell, an air inlet, blades, an impeller front cover plate, an impeller rear cover plate and a motor. The impeller front cover plate is separated from the blades. The inner side edge of the impeller front cover plate is connected with the air inlet. The outer side edge of the impeller front cover plate is connected with a drum fixed to the air inlet. The impeller front cover plate, the air inlet and the drum form a hollow cylinder, wherein the inner wall of the hollow cylinder is a smooth curved surface, and the inner diameter of the hollow cylinder is gradually increased from the middle to the two ends. A cavity is formed between the inner wall and the outer wall of the hollow cylinder. Through holes are formed in the surface, making contact with airflow, of the hollow cylinder, the punching rate is 20-30%, the diameter of the through holes is greater than or equal to 4 mm, and the cavity is filled with silencing materials. According to the silenced high-speed centrifugal fan provided by the invention, the blades are separated from the impeller front cover plate, the machining difficulty is remarkablyreduced, the blades and the impeller rear cover plate are integrally formed, and the fan pressure is increased; and the through holes are formed in the surface, making contact with the airflow, of the hollow cylinder, a dissipative muffler is formed, the airflow resistance is low, the pressure loss is low, and the noise reduction effect is good.