Abstract: Electrical resistance method has great prospects in structural health monitoring (SHM) of carbon fiber reinforced composites. The piezoresistive effect of carbon fiber 3D angle-interlock woven composites in the warp direction and weft direction under bending was investigated to find the relationship between the resistance variation and structure damage. The experimental results show that the resistance variation of the warp and weft samples under bending corresponded with the damage of the main load-bearing yarns. The resistance variation of the composite reflected the change in the load-bearing ability of the composite under the quasi-static three-point bending test. The electrical resistance did not change before the maxim load, while that increased after the main load-bearing yarns occurred breakage. The resistance variation of the composite reflected the degradation in the load-bearing ability of the composite under the bending fatigue test. In the early stage of the bending fatigue test, the negative piezoresistive effect of the composites was observed. The electrical resistance increased slowly due to the accumulation of the irreversible damage including matrix cracks and interface debonding, while that increased significantly after the main load-bearing yarns were damaged. The electrical resistance increased dramatically when the samples occurred fatigue failure.