A demodulation system for 3D-matrix multi-channel fiber optic sensing includes a wavelength swept optical source that generates an incident light, an optical frequency domain reflector and a balanced detector connected with the wavelength swept optical source through a fiber circulator. The optical frequency domain reflector includes a first optical path and a second optical path with a frequency shifter arranged on one or both of the optical paths. The optical frequency domain reflector outputs incident light to an optical switch module. The optical switch module selectively transmits the incident light to a sensor network as well as transmits the reflection light from the sensor network to the optical frequency domain reflector.