The invention relates to a method and device for measuring the percolating water area of a shield tunnel lining segment. The method comprises the specific steps of: calibrating a camera by adopting a computer vision tool kit; acquiring an image of segment percolating water, measuring a shooting distance and a shooting inclination by using a laser distance measuring instrument; carrying out lens distortion correction on the acquired percolating water disease image by adopting a division distortion model; converting the acquired image into a gray image; carrying out Blob analysis on an ROI (Region of Interest), i.e., determining a maximum threshold and a minimum threshold of the ROI, and carrying out threshold segmentation to obtain region characteristics in the image including the segment percolating water region; carrying out connecting Blob analysis on the image obtained through primary segmentation, and connecting all target pixels judged as percolating water regions into a block; filling and filtering the percolating water disease region by adopting an opening operation and a closing operation to obtain a final percolating water region; calculating the area of the percolating water region; correcting the area of the segment percolating water region; and figuring out the actual area of the segment percolating water region. The method and device have the advantages of low cost, high precision, rapidness and convenience, and the like.