A test system and a test method thereof. The test system includes an electronic device and a test device. The electronic device includes a plurality of output interfaces and provides a corresponding test signal via the output interfaces according to a group of operation commands. The test device includes a transforming unit, a multiplexer unit, a processor unit and a plurality of test interfaces which are respectively coupled to the output interfaces. The transforming unit transforms the test signals received via the test interfaces. The multiplexer unit selects the transformed test signals. The processor unit controls the multiplexer unit to select one of the transformed test signals, and determines whether the transformed test signal being selected conforms a predetermine condition for generating a test result signal. The processor unit controls the communication unit to transmit the test result signal to the electronic device according to the test result signal.