Abstract: The infrared small target de-noising in complicated background is studied. According to de-correlation and energy compaction of wavelet transforms, a new de-noising method is proposed. The method is put forward with the consideration of the practicality of the method, especially while the image involves complex background and a lot of noise. Firstly, the image is decomposed twice using wavelet transforms. Secondly, each wavelet detail coefficient is recalculated according to the new method in order to avoid the shortcomings of the hard or soft wavelet shrinkage. Lastly, the de-noised image is obtained by reconstruction from the processed coefficients. Simulation results show the de-noising method can preserve the shape character of small target, attenuate the background, and work efficient