The main chemical components in the natural fermentation of Huarong large-leaf mustard (HLLM) and Brassica juncea var. integlifolia(BJVI) were characterized. The results showed the mass fractions of water, fat, protein, vitamin C, amino acid nitrogen and phosphorus in BJVI were higher than those of HLLM, and the mass fractions of total soluble sugar, total acid, dietary fiber, calcium and iron in HLLM were higher than those of BJVI. The total amounts of glucosinolates in fresh HLLM were higher than those of fresh BJVI. The total amounts of glucosinolates in fresh HLLM and BJVI were 50.23, 46.38 μmol/g, respectively, and the total amounts of glucosinolates in stem bark, petiole, stem and leaf of fresh HLLM and BJVI decreased successively. The mass fractions of soluble total sugar, dietary fiber, protein, fat, vitamin C and the total amounts of glucosinolates in leaf mustard decreased with fermentation, the mass fractions of total acid and amino nitrogen increased with fermentation. 7 and 11 major volatile components were identified in fresh HLLM and BJVI, among which allyl isothiocyanate had the highest relative content, 92.83% and 85.98% respectively. A large number of volatile compounds were produced after fermentation of HLLM and BJVI, and a total of 93 compounds of 10 classes were identified, and allyl isothiocyanate decreased significantly. Therefore, it can be seen that fresh HLLM and BJVI have relatively comprehensive chemical components with a high total amount of glucosinolates, which has higher edible and application value. While fermented HLLM and BJVI have unique flavor and mellow taste.