The invention relates to a calibration device and a calibration method used for an indoor pyranometer. A supporting pillar and a positioning pillar are arranged on left and right surfaces of a rotating crossbeam respectively, and a rotating shaft is fixed in a bearing in a shaft core and is movably connected with a fixed shaft; a light shield is fixed at the bottom end of a light shield disc, theupper end surface of the light shield disc is fixed with a crossbeam of a photochopper, the crossbeam of the photochopper is placed in a U-shaped mouth on an upright shaft of the photochopper and is connected with the upright shaft of the photochopper through a pin shaft; and the upright shaft of the photochopper is fixed on a worktable board, a turn table is fixed on the worktable board, the crossbeam of the photochopper is rotated clockwise to enable the light shield of the photochopper to be placed above the turn table, a light source support is fixed on the rear end surface of the worktable, an irradiation light is movably connected on the light source support, and the distance between the irradiation light and the worktable board can be adjusted. The method is characterized in that the calibration can be performed indoor at any time, and is not limited or influenced by weather; the light source is stable, the calibration time is short, and the stability is high; and the use is convenient, the efficiency is higher, and the data reliability is high.