Abstract: The helium purification system of 10MW high temperature gas-cooled reactor consists of the purification equipments and their accessories. The purification equipments include a copper oxide bed, a molecular sieve absorber, a low temperature absorber, and etc. The gas sampling and analyzing system is consisted of the gas chromatograph, moisture probe, and infrared analyzing instrument. The moisture probe and infrared analyzing instrument both conform to the design requirement, and consecutive inspection of H₂O、CO、CO₂ can be carried out for the primary helium circuit. The gas chromatograph can also meet the design requirement, and so the intermittent sampling and analyzing of H₂O₂, N₂, CH₄, CO, and CO₂ can be carried out for the primary helium circuit.