To characterize phenotypic variation in soluble sugar content of soybean sprouts and to elucidate its genetic basis， we evaluated 188 improved soybean varieties from the Huang-Huai-Hai region. Soluble sugar content in germinated sprouts was accurately quantified in 2023 and 2024， followed by a genome-wide association study （GWAS） using SNP markers. Substantial phenotypic variation was observed， with soluble sugar content ranging from 1.67 to 20.94 mg/g and a coefficient of variation of 33.33% and 26.73%， indicating considerable genetic diversity for this trait. GWAS detected five loci significantly associated with soluble sugar content ［-log₁₀（P）≥5.86］ across two years， located on chromosomes 2， 10， 12， 14， and 18. Within these regions， 18 candidate genes were identified， with functional annotations enriched in carbohydrate metabolism pathways， including gluconeogenesis and trehalose synthesis， as well as cell wall biosynthesis. Expression analysis further showed that four candidate genes were differentially expressed between high- and low-sugar materials， supporting their potential roles in regulating soluble sugar accumulation. Overall， this study reveals the phenotypic diversity and genetic architecture of soluble sugar content in soybean sprouts from the Huang-Huai-Hai region. The identified loci and candidate genes provide valuable resources for functional marker development and marker-assisted breeding aimed at improving sprout quality.