Optical frequency domain reflectometry(OFDR) techniques and wavelength division multiplexing(WDM) techniques are applied to interrogating fiber grating array and tunable optical filter (TOF) to modulating multiplex signals. The fundamental principle of OFDR has been analyzed and the space resolution and measurement range of this system were calculated theoretically and then a sensor network of FBG array was experimentally demonstrated. Making full use of optical frequency and wavelength information, this system has shown the potentialities of interrogating and demodulating signals from several hundreds FBG sensors on the premise that power of light source is large enough. This system has good prospects in two or three-dimensional distribution stress monitoring of large structures.