This paper describes a calibration equipment, consisting of a 250 cm-diameter integrating sphere radiation source as its calibration source. It has a large radiation aperture (in diameter of 40 cm), high radiation power, high spatial uniformity and wide angle diffusion, with stable output and wide wavelength region of calibration (0.25 to 2.5 micrometer). The equipment can be used to calibrate optical remote sensors and other optical instruments used for measuring radiation in the near UV, visible, and near IR wavelenth regions.