A switching module is for connecting a Pulse Width Modulation (PWM) device to a plurality of fans under test. The switching module includes a print circuit board (PCB), and a plurality of groups of signal connectors arranged on the PCB. Each group of signal connectors includes a first port, a second port, and a third port interconnected with each other. The first port is for connecting to a testing port of an external PWM device. The second port is for connecting one corresponding fan of the plurality of fans. The third port is for connecting an interface of a server motherboard.