The Huaneng Shandong Shidao Bay Nuclear Power High-Temperature Gas-Cooled Reactor Demonstration Project is the only operating spherical bed modular reactor type in the world. The primary loop uses helium as the coolant, and to ensure the purity of the primary loop helium, a helium purification system is used to remove a variety of gaseous impurities. A copper oxide bed is set up in the helium purification system to oxidize hydrogen and methane in helium into water and carbon dioxide. The molecular sieve bed adsorbs water and carbon dioxide in helium, and the cryogenic adsorber removes inert gas and water and carbon dioxide that are not fully adsorbed upstream. When the helium purification system approaches saturation, it needs to be regenerated to restore its purification function. The waste gas after regeneration process of molecular sieve bed is emitted through the chimney, the waste gas after regeneration process of the cryogenic adsorber is stored in the KBQ waste gas storage tank, and decayed for 90 days before being emitted. This research focuses on the impact of gaseous effluent emissions on the activity concentration of nuclides after the primary loop helium purification system is regenerated. By taking samples and measuring the gaseous effluent, analyzing the trend of the activity concentration of nuclides in the gaseous effluent, obtained the rule of nuclide emission during the regeneration of the helium purification system, providing data support for the waste gas emission during the regeneration of the helium purification system in the demonstration project.