The invention relates to a vehicle-mounted insulated cabinet and an air supply outlet switch thereof. An air guide pipe is connected to an armrest box from a main air duct of an air conditioner through an adapter, and the air supply outlet switch is arranged at the joint of the air guide pipe and the armrest box. The air supply outlet switch comprises a knob, a switch cover plate, a switching plate, a spring, a support, a connecting rod and a shell, wherein the connecting rod is arranged in the shell through the support and the switch cover plate and can move relative to the support and the switch cover plate; the switching plate and the spring are arranged on the connecting rod and are positioned between the support and the switch cover plate, and the spring is positioned between the support and the switching plate; the switching plate can axially move along the connecting rod and can rotate together with the connecting rod so as to be matched with the switch cover plate, thereby realizing the purposes of opening and closing the air supply outlet of the insulated cabinet; and the knob is arranged at the right end of the connecting rod, can drive the connecting rod to rotate together, and is matched with the spring so as to push the switching plate to axially move along the connecting rod. The vehicle-mounted insulated cabinet and the air supply outlet switch are compact in structure, high in reliability and convenient to use.