Abstract: High-purity and low-background nitrogen plays an important role in the low-background experiments, and it is necessary to study radioactive impurities removal technology and low-background radon measurement in nitrogen. The research uses low-temperature adsorption technology to remove radioactive impurities in nitrogen. At the same time, electrostatic collection and low-temperature enrichment methods are combined to measure ~10 μBq/m³ radon in nitrogen. The result shows that the purification system can reduce the radon background in nitrogen by 20 mBq/m³ to (25.2±5) μBq/m³, namely, can reduce the radon background by 800 times. It is also found that the purification capacity is related to the radon background in nitrogen. In the range of radon background from dozens of mBq/m³ to dozens of μBq/m³, the purification capacity decreases with the lower radon background. The main reason is that the adsorption capacity decreases with the lower partial pressure of radon. In addition, the influence of radon pollution caused by system background and leakage increases significantly under very low background.