Fiber Bragg grating (FBG) sensors were applied for the monitoring of impact damage of composites. The FBG sensors were embedded into glass fiber reinforced vinyl resins (GFRP) laminates. Sectional appearance of the optical fiber embedded in composites was got by optical microscope. The composites were impacted by a drop-weight impact tester. The impact energies were 0.1J, 0.2J and 3J. The whole process was monitored by two different demodulators.