The invention relates to a method for detecting the corrosion degree of steel bars inside concrete based on infrared thermal imaging. The method comprises the following steps: applying electromagnetic excitation to the steel bars inside a concrete member to heat the steel bars, then collecting infrared thermograms on the surface of the concrete member, extracting the temperature change rate data through the infrared thermograms, and detecting the corrosion condition of the steel bars according to the temperature change rate data. The method has the technical benefits that the method can precisely position the corrosion area of the steel bars inside the concrete, is easy to operate, and is conducive to popularization.