Abstract: In order to solve the problem difficultly to identify the defect contour information in the infrared detection of wind turbine blades,a differential morphological gradient（DMG）edge enhancement method based on expansion corrosion is proposed in this paper.Firstly,the infrared thermal image of the defect is measured in the wind field experiments. Then,Sobel operator,Prewitt operator,dilation corrosion operator and DMG operator are employed to process the infrared image. Moreover,the four adjacent principle contrast is selected as the measurement standard. Furthermore,the original image is fused with the DMG image,and the fused image is enhanced by contrast limited adaptive equalization method. Finally,the enhanced image is displayed in the detection software. The experimental results show that the algorithm proposed in this paper can effectively enhance the edge contour information of defects,which solves the difficulty of detecting the contour recognition during blade infrared inspection.