The present invention discloses a signal processing system applicable in an electronic system having a hard disk, an indicator and an I/O controller, the I/O controller processing a driving signal outputted by the hard disk and generating a first processing signal. The signal processing system includes an editing module for editing a plurality of decoding modes, a detecting module for detecting a type of the I/O controller and outputting type messages corresponding to the detected type of the I/O controller; an acquiring module for acquiring the decoding mode from the editing module according to the type messages outputted by the detecting module; and a decoding module for decoding the first processing signal outputted by the I/O controller according to the decoding mode acquired by the acquiring module and generating a second processing signal to drive the indicator to operate, thereby simplifying the design and reducing the cost.