Faba bean is an important legume crop consumed as a vegetable or snack food, and its green cotyledons could present an attractive color for consumers. A mutation inSGRcauses stay-green in plants. In this study,vfsgrwas identified from a green-cotyledon-mutant faba bean, SNB7, by homologous blast between the SGR of pea and the transcriptome of faba bean. Sequence analysis revealed that a SNP at position 513 of the CDS ofVfSGRcaused a pre-stop codon, resulting in a shorter protein in the green-cotyledon faba bean SNB7. A dCaps marker was developed according to the SNP that caused the pre-stop, and this marker was completely associated with the color of the cotyledon of faba bean. SNB7 stayed green during dark treatment, while the expression level ofVfSGRincreased during dark-induced senescence in the yellow-cotyledon faba bean HST. Transient expression ofVfSGRinNicotiana. benthamianaleaves resulted in chlorophyll degradation. These results indicate thatvfsgris the gene responsible for the stay-green of faba bean, and the dCaps marker developed in this study provides a molecular tool for the breeding of green-cotyledon faba beans.