Fiber Bragg Grating (FBG) Sensor is very sensible to strain change, with 1.2 pm shift in Bragg wavelength when suffering 1 μm strain change [1]. Metal corrosion is big problem in our world. In order to monitor this process, many methods are proposed, but seldom focus on the strain change of metal plate during corrosion. One reason for this is that the strain change during corrosion is much smaller than the sensitivities of most sensors. Another problem is the residual strain left in metal products, which will also be released during corrosion without an obvious regularity. Our solution is applying a bending to the metal plate, keeping curvature radius at the medium of the metal plate unchanged during corrosion. As to the residual strain, which has a non-negligible influence in order of magnitudes, we set another metal plate made in same process without bending. By comparing the results of the bent and unbent plates, the strain changes only contributed by the bending during corrosion can be achieved. We calculate a model to analyze the strain changes contributed by bending during corrosion. The expected result is that the rate of strain change during corrosion is always in positive correlation with the corrosion speed. After 500 hours corrosion experiment, the low-carbon steel (0.13-0.20% Carbon) plate with 1.59 mm in thickness at the beginning corroded 0.1202 ±0.0088mm, the total strain change contributed by bending is 91.213 ±3.158με. The rate of strain change during corrosion for the results is positive during corrosion, fitting the expectation very well
