A switch-mode power supply waste heat recovery and utilization system includes a switch-mode power supply unit, an air conditioner and a water storage tank that are all connected with pipes. The switch-mode power supply unit, the air conditioner and the water storage tank are in communication with each other through the pipes. The switch-mode power supply unit includes a cabinet. Fixed plates are fixedly connected to an inner side wall of the cabinet and arranged at equal intervals. A top and a bottom of the cabinet and respective interiors of the fixed plates are formed with cavities. The pipes are in communication with the cavities. A fan is fixedly connected to a side wall of the water storage tank, and is matched with the water storage tank. A filter screen is insertedly connected to an inner side wall of the water storage tank. A filter cotton is horizontally provided under the filter screen.