This paper describes the method of Fiber Bragg Grating(FBG)embedded in the three-dimensional(3D) braded composite materials and provides the method of health monitor for 3D braided composite materials condition. The paper analyses the relations of FBG change and the inner straining under the stretching on materials. It is provided that the way of signal collection and processing. In the process of load-supporting, the internal local strain of 3D braided composites is much more, and local strain has certain interference on embedded near FBG output. The experimental results proved that FBG sensors have exceptional sense characteristic. The braided angle of composites has a little influence on FBG signal. FBG embedded in the 3D braided composite materials has not more effect mechanical property of materials. This research provides basis for the study and application of advanced intelligent composites.