Provided are a 3D reconstruction method and apparatus, an electronic device and a storage medium. The 3D reconstruction method comprises: using a plurality of cameras with different viewing angles to image a symbol to obtain a symbol image, a reference object for camera calibration being called the symbol, the symbol including a plurality of markers, and each of the markers having a corresponding ID number; identifying the ID number of the marker in the symbol image and searching for world coordinates corresponding to the marker according to the ID number; computing an external parameter matrix of the camera according to marker coordinates of a camera coordinate system and marker coordinates of a world coordinate system, and unifying point clouds under the world coordinate system to obtain a plurality of point clouds under different viewing angles; and stitching the plurality of point clouds together to obtain a 3D reconstructed image.