Based on the urgent need of calibration on high-resolution optical load, a series of calibration device for high-resolution optical load by spectrally tunable source were designed. The spectrally tunable source can produce any spectral display light from 300-800 nm, which is turned by spatial modulation and being at infinity, clear target. Spectrum parameter, radiation parameter, imaging performance parameter can be calibrated by the device. The calibration device′s spectral radiance ranges from 5.64×10-4-3.14×10-1(W·sr·m-2·nm-1). The calibration device′s spatial resolution accuracy is 0.059 mrad. The calibration device′s field of view ranges from 0 to 1°3′30″. The spectral radiance response non-uniformity is 0.39%. The basic principle, system design of the calibration device and detailed test results were introduced . Thus, the calibration device for the optical load has the advantages of arbitary spectrum modulation, scalable, high resolution.