The invention discloses a retinal vessel image segmentation method based on deep learning, and the method comprises the steps: carrying out the enhancement of a fundus image, amplifying the data of atraining set, constructing a dense connection convolution block, replacing a conventional convolution block with the dense connection convolution block, achieving the feature reuse, and improving thefeature extraction capability; constructing an attention mechanism module, and performing adaptive adjustment on the feature map to highlight important features so as to suppress invalid features; building a model, building a DA-Unet network, using the processed data set to perform training and parameter adjustment, and obtaining and storing an optimal segmentation model; and carrying out actual segmentation, segmenting the eye fundus image needing retinal vessel segmentation into 48 * 48 sub-block images by using a sliding window, inputting the 48 * 48 sub-block images into a DA-Uet network for segmentation, outputting segmented sub-block image results, and splicing the segmented small block images into a complete retinal vessel segmentation image. The blood vessel segmentation method canautomatically segment blood vessels and has a good segmentation effect on tiny blood vessels.