The vein images collected by using the principle of vein recognition are usually blurred and difficult to distinguish. The traditional CLAHE algorithm can improve the contrast of vein images, but will lose some details of the image. Therefore, a vein enhancement algorithm based on CLAHE and multi-scale detail fusion is proposed. Firstly, the ROI of the vein image is extracted, and the CLAHE algorithm is used to enhance the contrast between the vein and the back of the hand. Then, the multi-scale detail fusion algorithm is used to obtain the detailed image of the vein image, and then the high-frequency noise is filtered out in the detail layer through the average filter. Finally, the images obtained by the two methods are weighted and superimposed to obtain vein images with enhanced details. Experimental results show that this method not only improves the contrast of the vein images, but also retains the details of the original images.