In order to realize high precision measurement of spectral radiance, a kind of small field near ultraviolet(UV) to near infrared(IR) spectroradiometer was developed with a wavelength range of 300 nm~ 2 000 nm and a spectral radiance measurement range of 50 μW/cm2·nm·sr~1 000 μW/cm2·nm·sr. First the design principle and critical components of the near-UV to near-IR spectroradiometer were described. Then the direct method based on tungsten strip lamp was used to realize the spectral radiance absolute calibration of this spectroradiometer. Finally, the spectral radiance of the standard integrated sphere source was measured. The results show that the deviation between measured and standard values is less than 0.5%.