The present disclosure discloses a transmitter and a monitoring system using this transmitter, the transmitter includes: a multi-to-one multiplexing switch configured to receive a plurality of sensor signals of a plurality of channels through a plurality of input terminals, select one sensor signal from the plurality of sensor signals, and output the selected sensor signal through a output terminal; a first variable gain amplifier configured to receive the selected sensor signal, amplify the selected sensor signal with a gain within a first gain range, and output the amplified sensor signal; a control parameter input terminal configured to receive an input control parameter from outside of the transmitter; and an operating and switching selector configured to perform operations according to the input control parameter, so as to control the multi-to-one multiplexing switch to select the one sensor signal and control the gain of the first variable gain amplifier.