The present paper aimed to investigate the relationship between physicochemical properties, flavor, and mi-croorganisms during the natural fermentation of Dendrocalamus giganteus Munro bamboo shoots. The pH dramatically decreased within 7 days and then stabilized at about 3.6. The total titratable acidity (TTA) values increased for 35 days, then decreased and stabilized at 24.34 g/L. Malic acid, lactic acid, and tartaric acid were the main organic acids (OAs) in sour bamboo shoots. Umami amino acids were the most important amino acids (AAs). The key volatiles (phenols, alcohols, and aldehydes) contributed most to the formation of the flavor of sour bamboo shoots. At the phylum level, Firmicutes, Proteobacteria, and Bacteroidota were the main phyla in sour bamboo shoots. At the genus level, Lactobacillus, Weissella, and Lactococcus were the main genera in sour bamboo shoots. Pearson correlation analysis showed that Firmicutes were significantly positively correlated with fumaric acid and negatively correlated with heptanal. The characteristic flavor (p-cresol) of sour bamboo shoots was negatively correlated with Cyanobacteria and Leuconostoc and positively with Lactobacillus. This study provided a theoretical basis for revealing the flavor formation mechanisms related to microbial composition in sour bamboo shoots and the screening of functional strains.