Abstract: Image enhancement is very important in infrared defect detection of wind turbine blades. Aiming at the problem of low image definition in infrared detection,an adaptive iterative threshold weighted difference top-hat transform infrared image enhancement method（AITWD top-hat）is proposed in this paper. Firstly,multiple groups of top-hat information are obtained by multi-scale white tophat and black top-hat transformation. Secondly,in order to obtain more image detail features,using the Contrast improvement ratio（CIR）as the threshold function,an iterative threshold image weighting method is proposed,and the optimal scale set image is fused to obtain the enhanced image. Finally,the proposed method is compared and verified with the existing methods from both qualitative and quantitative aspects. The experimental results show that this method not only has good image detail enhancement effect,but also effectively overcomes the problem of poor stability in traditional morphological image enhancement,the PSNR value and SSIM value are increased by 9.01% and 9.07% respectively.