In this paper, effect of FBG coating in curing monitoring of composites was studied. In the experiment, three kinds of sensors were embedded in the composites. Excursion of the wavelength and temperature was tested in the whole curing process. 3-point bending test of composites which FBG was embedded in was done. Results showed that FBG could be exactly reflecting the relationship of stress and strain in bending state of composites. After cured, composites were heat up to 180°C for 1 hour. Sectional appearance of different optic fibers in room temperature and high temperature was got by optical microscope.