A 3D image reconstructing method using X-ray volume photography acquires a plurality of X-ray area array images of the object interested according to locating principle of the digital photographic measurement. A plurality of mark points of the known 3D positions are simultaneously taken in the X-ray photo, and the method uses the coordinates of the mark points in the rectangular coordinate system for volume photographic 3D image reconstruction and the coordinates of the mark points in the X-ray photo coordinate system to construct a transforming relationship of the two coordinate systems. The method determines the path and the position of each X beam by using the transforming relationship and gets all voxels of each X-ray passing the object interested. The method uses the voxel g and the pixel G of the same X beam path to get Radon set of equations to determine the gray scale value of voxel g, then determines the gray scale values of all voxels g by computer and reconstructs a 3D volume image of the object interested based on the gray scale value of voxel g.