Abstract: To investigate the regulatory mechanism of exogenous yeast assimilable nitrogen (YAN) on the flavor quality of Huangjiu, this study used ammonium chloride (NH₄Cl), arginine (Arg), and glutathione (GSH) as exogenous nitrogen sources. Through simulated fermentation experiments, the effects of YAN on the physicochemical indices, volatile components, free amino acids and organic acids of Huangjiu were systematically analyzed, and sensory evaluation was conducted to verify the differences in flavor quality. The results showed that the total sugar (22.04 g/L) and total acid (7.36 g/L) in the NH₄Cl group were significantly higher than those in the control group (without exogenous nitrogen addition). The Arg group had the optimal accumulation of amino acid nitrogen (0.58 g/L), with targeted enrichment of umami amino acids and an increase in ester types to 19. It also had the lowest total sugar (14.04 g/L) and total acid (4.68 g/L), as well as the highest total organic acids. The GSH group had the highest ethyl hexanoate content, with the smallest flavor difference from the control group, a 14% increase in total free amino acids, and targeted enrichment of flavor-harmonizing organic acids such as succinic acid. Principal component analysis confirmed significant differences in volatile compounds driven by different YAN sources (cumulative variance contribution rate 75%), among which Arg and GSH optimized the flavor balance by regulating ester synthesis and amino acid metabolism. Sensory evaluation indicated that the Arg group performed outstandingly in wine aroma intensity and wine body fullness, while the GSH group had the best aroma coordination and aftertaste persistence. In summary, exogenous nitrogen sources differentially regulated the flavor quality of Huangjiu by modulating yeast amino acid metabolism and ester synthesis pathways: NH₄Cl was suitable for higher alcohol control, Arg was conducive to umami enhancement and ester diversity expansion, and GSH had similar flavor characteristics to the control group and could maintain flavor stability. This work provides a theoretical foundation for precise nitrogen regulation in Huangjiu fermentation processes.