Abstract: An image pre-processing method based on shearlet transform was proposed.First,image was decomposed by shearlet transform,then to get the subband coefficients,Bayesian statistics and threshold shrinkage methods were used in the low-frequency component and high—frequency components,through shearlet reconstruction,the predicted background of the image was obtained,the original image is subtracted by the predicted background image and we can get the result image,Finally,in order to test the new method,classical adaptive threshold segmentation was used to segregate the targets.Theoretical analysis and experimental results show that,compared with several commonly used methods,ISNR of result image which using the new method is higher than the others,and have better effects both in objective evaluation and the subjective vision.