1. A digital radiology (DR) lung contour extraction method based on fully convolutional network, comprising the steps as follows: establish the fully convolutional network structure of lung contour segmentation; conduct off-line training on weighting parameters of the fully convolutional network; read a DR image and the weighting parameters of the fully convolutional network; input the DR image into the fully convolutional network, output segmentation results of image through a network terminal with a network layer-by-layer feedforward and establish the lung contour in accordance with the segmentation results.