The invention relates to the technical field of lane line detection, in particular to a method and device for detecting a lane line. The method comprises: step a, acquiring multiple frames of continuous images shot by a shooting device; step b, carrying out edge detection and feature extraction on all frames of images to obtain image features, determining whether the image features corresponding to all frames of images match a preset lane line feature, and if so, obtaining a lane line model feature based on all image features; step c, acquiring a next frame of image shot by the shooting deviceafter obtaining of the lane line model feature as a first frame of image; and step d, carrying out edge detection and feature extraction on the first frame of image to obtain a first image feature, matching the first image feature with the lane line model feature, and in a matched state, updating the lane line model based on the first image feature and outputting a first image, and returning to the step c. With the method provided by the invention, problems of low stability and low reliability of the lane line detection result are solved.