How to measure the volume of express cartons simply and accurately is a difficult point in smart logistics. This study takes the express cartons in the logistics industry as the research object and proposes an algorithm for accurately measuring the volume of express cartons based on a 3D reconstruction network. To calculate the actual length of the carton, the image preprocess part segments the picture into express carton and background. Then the algorithm uses the 3D reconstruction network to obtain the voxel model of the express carton. Finally, removing the noise by the post-processing module, the algorithm gets the volume of the express carton. As the experiments show, the proposed algorithm improves the 3D reconstruction performance and obtains the volume of the express carton simply and accurately.