Abstract: Fiber Bragg grating (FBG) sensors are used to monitor fractures including slips, disengages and cracks of steel-concrete composite structure model. The test undergoes three phases：dead load test phase，fatigue test phase (3106 cycles), and destructive test phase. The results show that no fracture occurred during the first two phases. The data measured were the concrete strain of the location where the FBG sensor embedded. During the destructive test phase, structural cracks, slips and disengages occurred one after another and were measured by the FBG sensors. The critical strain values of the three kinds of damages were detected. The results demonstrate that the fractures of composite structures and their development processes can be detected and traced by means of FBG sensors, thereby this technique is useful for the health monitoring and optimal design of composite structures.