Abstract: Moldy amaranth stalk was a fermented food with national and regional characteristics, and volatile compounds determined the flavor quality of moldy amaranth stalk. In this study, the volatile flavor components of three kinds of commercially available moldy amaranth stalks from different origins in Zhejiang Province were analyzed. Electronic nose testing showed that Product B (Ningbo) had the highest inorganic sulfide flavor strength. A total of 117 volatile flavor components, including 32 alcohols, 15 aldehydes, 20 esters, 11 ketones, 5 acids, 6 phenol, 12 olefins, 10 alkanes, and 2 ethers, were detected in the three moldy amaranth stalks by solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) among them. There were 35 components with the aromatic activity value (OAV) of more than 1 in Product A (Shengzhou), 28 in Product B (Ningbo), and 40 in Product C (Shaoxing). p-Cresol and n-Nonanal were confirmed as an important marker, contributing to the smoky, herbal and vinegary flavors. Principal component analysis showed that the volatile flavor components of the three products were significantly different. Orthogonal partial least squares discriminant analysis screened 75 components with VIP values greater than 1, of which 29 components had OAVs greater than 1. Linalool and n-Heptanol were identified as an important differentiator of the moldy amaranth stalks, contributing to the floral and pungent flavors. This study provides a theoretical basis for further research on the fermentation process of moldy amaranth stalks.