Abstract: The antibacterial effects of cinnamon essential oil and cinnamaldehyde on bacteria(Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and fungi(Candida albicans) were compared by filter paper method, minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC). The antioxidant activities of cinnamon essential oil and cinnamaldehyde were compared by ABTS⁺· scavenging ability and ferric reducing antioxidant power(FRAP), as well as their antityrosinase activities were compared. The results showed that the two research subjects showed different sensitivities to the inhibitory effects of the five tested strains, and both had the best inhibitory effect on C. albicans. According to the results of MIC and MBC, cinnamic essential oil and cinnamaldehyde had different inhibitory effects on the tested strains, among which the inhibitory effects of cinnamaldehyde on S. aureus, C. albicans and P. aeruginosa were obviously better than those of cinnamon essential oil. The antioxidant activity of cinnamic essential oil was better than that of cinnamaldehyde. The ABTS⁺· scavenging rate(94.1%) of 16 g/L cinnamic essential oil was 3 times that of the same concentration of cinnamic aldehyde. The FRAP value(1 502 μmol/L) was 5.8 times that of cinnamaldehyde at the same concentration. Both cinnamon essential oil and cinnamon aldehyde could significantly inhibit tyrosinase activity. The IC₅₀ of cinnamon essential oil to tyrosinase was 4.02 g/L, while the IC₅₀ of cinnamaldehyde to tyrosinase was less than 1.25 g/L.