Aiming at the problem of lacking national measurement ability of short UV spectral irradiance, based on high temperature blackbody source, national primary standard apparatus of spectral irradiance in the spectral wavelength from 200 to 400 nm was developed independently at NIM in 2017. A group of stable deuterium lamps were used to maintain and disseminate the scale of spectral irradiance in short UV wavelength. New traceability system based on deuterium lamps was setup to provide the highest standard for the application fields. As to temperature measurement, spectral bandwidth, signal to noise ratio, fluorescence in the system, series new methods and key measurement technology were adopted to cut down the main error sources. The temperature measurement of blackbody was traced to Pt-C and Re-C fixed point blackbody, and checked against the WC-C fixed point blackbody. The deviation between NIM and VNIIOFI (All Russian Research Institute for Optical and Physical Measurements) at 3 021 K was 0.07 K, and measurement uncertainty at 200 nm was cut down by 0.2%. Owing to the great difference of spectrum between blackbody and deuterium lamp, the bandwidth effect of the monochromator should be considered. A seven point bandwidth novel correction method based on differential quadrature formula was put forward to correct bandwidth error 0.86% at 200 nm. Absolute and relative measurement principle was adopted to reduce the repeatability uncertainty about 20 times at 200 nm. A selective filter method was used to remove fluorescence in the primary standard apparatus. The standard measurement uncertainty of temperature was 0.64 K when BB3500 M blackbody was operating at 3 021 K, and the non-uniformity was less than 0.17 K over the effective diameter. The maximum shift of the temperature of the blackbody was less than 0.2 K during measurement period. Wavelength error of the double grating monochromator was less than ±0.01 nm. The standard measurement uncertainty of the secondary primary standard of spectral irradiance were 4.0% at 200 nm, 1.3% at 250 nm, 1.2% at 330 nm, 1.9% at 400 nm respectively. The establishment of new primary standard apparatus is based on deuterium lamps from 200 to 400 nm, which is possible for NIM to participate the international key comparison CCPR-K1. b sponsored by the International Bureau of Weights and Measures (BIPM). Wavelength range of the new primary standard is linked up with the original primary standard of spectral irradiance based on tungsten halogen lamps. In the overlap wavelength from 250 to 400 nm, the average deviation between two kinds transfer standard lamps, deuterium lamp and tungsten halogen lamp, was verified to be less than 0.39%, which was consistent with the associated measurement uncertainty.