A cabinet, comprising a cabinet body and at least one device disposed in the cabinet body, wherein the cabinet body is further provided with at least one air duct system, and the air duct system comprises: a plurality of air deflection parts and an air baffle that is scalable along an insertion direction of the device, wherein one end of the air baffle is connected to an inner wall of the cabinet body, and the other end of the air baffle presses against the device; the plurality of air deflection parts are disposed along the air baffle in the cabinet body, wherein an interval exists between two adjacent air deflection parts; and when the device is inserted into a spacing, the plurality of air deflection parts and the air baffle divide inner space of the cabinet body into a cold air duct and a hot air duct that are isolated from each other, wherein the interval and the spacing coincide; wherein an air intake vent of the device and an inner wall that is of the cabinet body and on which an air intake vent is provided are both located in the cold air duct; an air exhaust vent of the device and an inner wall that is of the cabinet body and on which an air exhaust vent is provided are both located in the hot air duct; one side of the plurality of air deflection parts, one side of the air baffle, and some inner walls of the cabinet body enclose to form the cold air duct; and the other side of the plurality of air deflection parts, the other side of the air baffle, and remaining inner walls of the cabinet body enclose to form the hot air duct; characterized in that each air deflection part is an air deflection part with an adjustable length; and one end of each air deflection part is connected to the air baffle, and the other end of each air deflection part is connected to an inner wall of the cabinet body; or a guide rail is disposed at one end of the air baffle that faces the device, both sides of the guide rail are provided with a sliding slot for the air deflection part to pass through, one end of the air deflection part is connected to an inner wall of the cabinet body, the other end of the air deflection part passes through one of the sliding slots and extends to the end of the air baffle that is connected to the cabinet body, and the guide rail slides on the air deflection part when the air baffle is compressed. a plurality of air deflection parts and an air baffle that is scalable along an insertion direction of the device, wherein one end of the air baffle is connected to an inner wall of the cabinet body, and the other end of the air baffle presses against the device; the plurality of air deflection parts are disposed along the air baffle in the cabinet body, wherein an interval exists between two adjacent air deflection parts; and when the device is inserted into a spacing, the plurality of air deflection parts and the air baffle divide inner space of the cabinet body into a cold air duct and a hot air duct that are isolated from each other, wherein the interval and the spacing coincide; wherein an air intake vent of the device and an inner wall that is of the cabinet body and on which an air intake vent is provided are both located in the cold air duct; an air exhaust vent of the device and an inner wall that is of the cabinet body and on which an air exhaust vent is provided are both located in the hot air duct; one side of the plurality of air deflection parts, one side of the air baffle, and some inner walls of the cabinet body enclose to form the cold air duct; and the other side of the plurality of air deflection parts, the other side of the air baffle, and remaining inner walls of the cabinet body enclose to form the hot air duct; characterized in that each air deflection part is an air deflection part with an adjustable length; and one end of each air deflection part is connected to the air baffle, and the other end of each air deflection part is connected to an inner wall of the cabinet body; or a guide rail is disposed at one end of the air baffle that faces the device, both sides of the guide rail are provided with a sliding slot for the air deflection part to pass through, one end of the air deflection part is connected to an inner wall of the cabinet body, the other end of the air deflection part passes through one of the sliding slots and extends to the end of the air baffle that is connected to the cabinet body, and the guide rail slides on the air deflection part when the air baffle is compressed.