A calibration method of a combined device, wherein the combined device comprises a shape measurement light projector configured to irradiate shape measurement light; a shape measurement camera configured to obtain a surface shape image of a target by detecting reflected light formed by the shape measurement light being reflected by a surface of the target; and an optical coherence tomography measurement unit configured to transmit layer measurement light through the target, detect reflected light reflected by the surface and internal layers of the target, and obtain surface and internal cross-sectional images of the target, the calibration method comprising: irradiating the shape measurement light to a calibration target, obtaining a surface shape image of the calibration target by detecting the reflected light formed by the shape measurement light being reflected by the surface of the calibration target by using the shape measurement camera, and calibrating the surface shape image of the calibration target obtained by the shape measurement camera according to an actual shape of the calibration target; obtaining surface and internal three-dimensional images of the calibration target by scanning the calibration target with the layer measurement light by using the OCT measurement unit, extracting a surface shape image of the calibration target from the three-dimensional images, and calibrating the surface shape image of the calibration target obtained by the OCT measurement unit according to the actual surface shape of the calibration target; and matching a calibration image obtained by the shape measurement camera and a surface calibration image obtained by the OCT measurement unit so as to be displayed at the same spatial coordinates, wherein the calibration target is a non-transmissive planar target having a pattern of a predetermined shape uniformly formed on a surface thereof, the three-dimensional images of the calibration target obtained by the OCT measurement unit has a surface image which is clear and an internal image which is relatively opaque, and when a two-dimensional surface shape image is extracted from the three-dimensional images obtained by the OCT measurement unit, the two-dimensional surface image corresponds to the surface shape image of the calibration target obtained by the shape measurement camera, and the two-dimensional surface image is used to carry out image calibration of the OCT measurement unit. irradiating the shape measurement light to a calibration target, obtaining a surface shape image of the calibration target by detecting the reflected light formed by the shape measurement light being reflected by the surface of the calibration target by using the shape measurement camera, and calibrating the surface shape image of the calibration target obtained by the shape measurement camera according to an actual shape of the calibration target; obtaining surface and internal three-dimensional images of the calibration target by scanning the calibration target with the layer measurement light by using the OCT measurement unit, extracting a surface shape image of the calibration target from the three-dimensional images, and calibrating the surface shape image of the calibration target obtained by the OCT measurement unit according to the actual surface shape of the calibration target; and matching a calibration image obtained by the shape measurement camera and a surface calibration image obtained by the OCT measurement unit so as to be displayed at the same spatial coordinates, wherein the calibration target is a non-transmissive planar target having a pattern of a predetermined shape uniformly formed on a surface thereof, the three-dimensional images of the calibration target obtained by the OCT measurement unit has a surface image which is clear and an internal image which is relatively opaque, and when a two-dimensional surface shape image is extracted from the three-dimensional images obtained by the OCT measurement unit, the two-dimensional surface image corresponds to the surface shape image of the calibration target obtained by the shape measurement camera, and the two-dimensional surface image is used to carry out image calibration of the OCT measurement unit.