A multi-channel detecting system is disclosed. The multi-channel detecting system includes one or more signal-generating units, one or more detecting units, one or more amplifying units, and a calibration unit; the one or more signal-generating units are configured to provide a plurality of signals, the one or more detecting units are configured to detecting a plurality of signals from the one or more signal-generating units and transmitting through a plurality of calibration samples and generating corresponding quantized values; the one or more amplifying units electrically connected to the one or more detecting units are configured to amplify the quantized values; the calibration unit electrically connected to the one or more amplifying units is configured to calibrate the one or more amplifying units to make amplified quantized values provided by the amplifying units to be equal to one or more specific values.