Disclosed is a low-noise air source heat pump. The low-noise air source heat pump comprises a housing (1), an evaporator (15), a centrifugal fan blade (3), a compressor (4), a heat exchanger (5), etc., wherein the centrifugal fan blade (3) is mounted in a dedicated centrifugal fan holder (2), and by means of a side air duct (22) on the centrifugal fan holder (2), air outflow of the centrifugal fan blade (3) is led out from a side face. Since the centrifugal fan blade (3) can still meet an air flux during the working of the air source heat pump and under the premise of a low rotation speed, working noises such as component vibration and airflow disturbance generated in an operation process of the fan blade can be reduced, and the propagation and diffusion of the noise are also greatly reduced by means of side air outflow. Moreover, an air guide sleeve (6) is additionally provided between the evaporator (15) and the centrifugal fan holder (2), an air guide hole (61) protruding towards the centrifugal fan holder (2) is provided on the air guide sleeve (6), and the air guide hole (61) and the centrifugal fan blade (3) are located on the same axis line. The structure not only ensures the usage advantages of the centrifugal fan blade (3), but also solves the problem of the middle of the evaporator (15) being prone to frost due to the air suction centralization of the centrifugal fan blade (3).