The utility model relates to an optic fibre light path exchange device and detection system, optic fibre light path exchange device, including programmable logic controler, configuration treater and a plurality of fiber optical transceiver, programmable logic controler for go on the signal of telecommunication of two fiber optical transceivers alternately at the internal network, the fiber optical transceiver is used for connecting optic fibre, carries out photoelectric conversion to optical signal, the configuration treater for provide communication interface such as serial ports / ethernet, and assign configuration instruction to programmable logic controler through the interface. Compared with the prior art, the utility model provides an optic fibre light path exchange device can carry on special data communication protocol. And in the devices such as narrow and small underwater robot in space -rated or scuba, when facing the condition such as height vibrations as operating environment, also can normally work.