K fluorescence radiation device can fill the metrological verification needs of super large measuring area nuclear radiation detector in China. The device has the advantages of high flux, many energy points, good monochromaticity, low cost and is ready to use. The principle is that the X-ray emitted by the X-ray machine bombards the radiator material to produce a variety of characteristic X-rays, namely fluorescent rays. A secondary filter is added to the fluorescent ray emission path to absorb the excess rays and improve fluorescent purity. The material thickness of the radiator and the secondary filter is directly related to the fluorescent yield and purity. The results of various index parameters of the fluorescent device are calculated by the Monte Carlo program to guide the establishment and research of the later test device. The data of Cs₂SO₄ radiator simulated by MCNP5 software show that the fluorescent device has good shielding and collimation effect, and the fluorescence is symmetrical and gradually decreases in the vertical plane of the radiator Center; The fluorescence yield increases with the increase of radiator thickness, but there is a relative saturation thickness; In order to obtain a single energy fluorescence radiation field, a secondary filter TeO₂ material is added in the direction of the fluorescence beam, which absorbs L and K_β The ray will be much greater than K_α Radiation; When the thickness of the secondary filter is 0.035 cm, the fluorescence purity of 94.521% is the maximum and the fluorescence yield is the highest; The fluorescence purity first increases and then decreases with the increase of the thickness of the secondary filter material; The energy spectrum data of K fluorescence radiation device is obtained through the actual measurement of the detector, and the energy spectrum data is processed and analyzed by root program to fit K_α1, K_α2. The peak location error of the energy point is less than 0.005%. The deviation between energy value and the theoretical value is 0.19% and 0.23% respectively, and the results are consistent. The measurement results can verify that the secondary filter material calculated by the MCNP5 program has a good absorption effect and realizes the single energy Fluorescence reference radiation field.