In order to solve the structured background suppression which is a difficult problem for infrared dim target detection technique,a method of infrared dim target background suppression based on DT-CWT is presented,considering the shift invariance,directional selectivity and perfect reconstruction of dual-tree complex wavelet transform (DT-CWT),Firstly,the image is decomposed by DT-CWT to extract the multi-scale detail characteristics,then wavelet coefficients of each decomposed level is adjusted nonlinear with a Max-Median filter to change the target strength,and the estimated background image is obtained by wavelet reconstruction.The result image is obtained by subtracting the background image from the original image.Based on the real IR image sequences,the experimental results demonstrate that compared with the two-dimensional least mean square error method,the presented method has good effects both in the subjective vision and numerical indices.