An air duct assembly is provided that is configured to supply air to a compartment and including: an outer cover housing, configured to be fixed to an outer side of a compartment wall defining the compartment, an external accommodating cavity being defined inside the outer cover housing; an inner cover housing, configured to be disposed opposite to the outer cover housing on an inner side of the compartment wall, an internal accommodating cavity being defined inside the inner cover housing. An air inlet is formed in the outer cover housing, so as to allow external air to enter the external accommodating cavity via the air inlet. A vent is formed in the compartment wall, so that the external accommodating cavity communicates with the internal accommodating cavity. An air outlet is formed in the inner cover housing, so as to supply the air in the internal accommodating cavity to the inside of the compartment.