Abstract: A test system, a test signal auxiliary device, and a test signal generation method thereof are disclosed. The test signal auxiliary device is used for providing a computer system to test a signal measurement device. The test signal auxiliary device includes a first signal input terminal used for receiving an analog test signal via a first audio port of the computer system. A filter module is used for filtering the analog test signal to produce a filtered signal. A first signal output terminal is used for outputting the filtered signal to the signal measurement device. A second signal input terminal is used for receiving a corresponding signal from the signal measurement device. A second signal output terminal is used for transmitting the corresponding signal to the computer system via a second audio port.