Ag₂S quantum dots (QDs) are a promising candidate for biomedical imaging, labeling and sensing. However, coating a ZnS shell on the Ag₂S QDs to improve the quantum yield (QYs) is still a challenge. Here, we developed a novel non-injection approach for synthesizing Ag₂S and Ag₂S/ZnS core/shell QDs using alkanethiols as both ligand and sulfur sources. The QY was significantly increased after coating a ZnS shell on the Ag₂S core. Moreover, the possible pathway of the sulfur released from the alkanethiol and transferred to the Ag₂S QDs, which is beneficial for understanding the formation mechanism of thiol-based non-injection synthesis of metal sulfide nanocrystal (NCs), was investigated.