Abstract: Developing sustainable packaging materials that combine excellent preservation performance with environmental friendliness remains an important direction in the field of food packaging. In this study, sulfur quantum dots (SQDs) with abundant amino groups on their surface were employed as multifunctional nanofillers and subsequently compounded with polyacrylic acid (PAA) and polyvinyl alcohol (PVA) to successfully construct a composite film material with multiple functions. Benefiting from the covalent crosslinking between SQDs and PAA as well as the strong hydrogen bonding interactions with PVA, the material formed a dense three-dimensional network structure, leading to significantly enhanced mechanical properties and water vapor barrier performance. Meanwhile, the inherent multifunctional characteristics of SQDs endowed the composite film with multiple advantages, including efficient UV shielding capacity, excellent antibacterial activity, and superior free radical scavenging performance, effectively overcoming the limitation of single-functionality commonly observed in traditional packaging materials. The results of preservation experiments on litchi demonstrated that the composite film significantly delayed fruit spoilage, inhibited water loss, maintained fruit firmness, and stabilizes pH, thereby extending the shelf life. Moreover, the composite film exhibited outstanding environmental sustainability, achieving near-complete biodegradation within 28 days and demonstrating good recyclability. This study provides an effective approach for the development of novel green high-performance food packaging materials.