An image generation system for implant diagnosis includes a first image information acquirement apparatus acquiring first three-dimensional (3D) image data about a mouth area of a target patient, a second image information acquirement apparatus acquiring second 3D image data by scanning plaster patterns of teeth of the target patient, and a data processing apparatus receiving and matching the first 3D image data and the second 3D image data and generating synthetic 3D image data. In the image generation system, the plaster patterns of teeth are provided with a matching reference marker for matching the first 3D image data and the second 3D image data, and the data processing apparatus pre-matches the first 3D image data and the second 3D image data based on a coordinate of a matching reference marker of the second 3D image data.