Abstract: Cinnamon essential oil, a mixture of volatile secondary metabolites from Cinnamomum spp., is widely utilized in the food and pharmaceutical industries due to its distinctive aroma and bioactivities. However, its chemical composition is highly influenced by various factors such as species, environment, and plant part, and the intrinsic relationship between the chemical composition of cinnamon essential oil and its functional properties remain inadequately clarified. This review provides a systematic overview of recent advances in understanding the chemical composition and functional activities of cinnamon essential oil. It first summarizes the key factors—genetic background, cultivation conditions, and plant part—that determine the chemical profile. It then discusses the contribution of major constituents (e.g., trans-cinnamaldehyde and 2-methoxycinnamaldehyde) to main bioactivities such as antimicrobial and antioxidant properties. Finally, the review synthesizes the interconnections among three dimensions: “raw material source (species, environment, and plant part), chemical composition (key components and their concentrations), and functional properties (e.g., antimicrobial and antioxidant activities)”. This review aims to provide a theoretical foundation for enhancing the quality control of cinnamon essential oil and enabling its standardized application.

Key words: cinnamon essential oil; chemical composition; influencing factors; functional activity