The invention provides an air supply system for a sleeper compartment and belongs to the technical field of rail vehicles. The air supply system for the sleeper compartment comprises a main air duct,an upper berth air duct, a lower berth air duct, a transverse wall air duct, an upper berth air volume adjusting device and a lower berth air volume adjusting device, wherein the main air duct is arranged in a compartment roof; an upper berth branch air duct and a lower berth branch air duct are connected to the main air duct; the upper berth air duct and the lower berth air duct are arranged outside a compartment side wall in the longitudinal direction of the compartment; the upper berth air duct communicates with the main air duct through the upper berth branch air duct; an upper berth air outlet for providing fresh air to an upper berth is formed in the upper berth air duct; the transverse wall air duct is arranged in a transverse wall; the transverse wall air duct communicates with themain air duct through the lower berth branch air duct; the lower berth air duct communicates with the transverse wall air duct; a lower berth air outlet for providing fresh air to the lower berth isformed in the lower berth air duct; the upper berth air volume adjusting device is arranged in the upper berth air outlet; and the lower berth air volume adjusting device is arranged in the lower berth air outlet. According to the air supply system for the sleeper compartment, air can be correspondingly supplied to the upper berth and the lower berth, and the air supply volume is adjustable.