In order to meet the requirements of laboratory radiometric calibration for continually rising optical aperture of optical remote sensors, 4 m extended uniform source for radiometric calibration is designed based on near extended source method. The maximum integrated radiance in the range of 400 nm to 900 nm is 200 W/(m2
·sr). The diameter of the calibration source is 4 000 mm and the exit port diameter is 1 600 mm. The opto-mechanical parameters of the calibration source are designed in detail. Using fiberoptic spectrometer to monitor relative spectral distribution, the calibration source can realize intelligent programmable remote control through CPLD combined with SCM to export specific integrated radiance. The maximum integrated radiance in the range of 400 nm to 900 nm is measured 222.62 W/(m2
·sr) using PR 735 spectrum radiometer. The measure uncertainty of the calibration source is analyzed by testing the radiation characteristics, including the stability, the uniformity,the lambertian, and the value is 3.57%. From the experimental results,the calibration source can satisfy the laboratory calibration needs for the visible/near-infrared optical remote sensors with the optical aperture under 1 600 mm. Meanwhile it can realize intelligent programmable control to improve the calibration accuracy.