Quince (Cydonia oblonga Mill.) is the one and only specie of the genus Cydonia in the Rosacea family. Quince contains bioactive constituents such as alkaloids, saccharides, flavonoids, and volatile oils. Nevertheless, seldom researches have concentrated on quince essential oil (QEO). The chemical composition, cellular activity, antioxidant activity, and α-glucose inhibition activity of the plant were studied. QEO was isolated using hydrodistillation technique, and the yield was 1.3 mL/kg. A total of 52 chemical constituents in QEO were determined by gas chromatography-mass spectrometry (GC–MS). The main components (> 3.0%) found in the QEO were methyl (Z)-octadec-6-enoate (16.2%), methyl linoleate (10.0%), cedrenol (8.8%), methyl hexadecanoate (7.2%), methyl palmitoleate (7.2%), dibutyl phthalate (5.4%), hexadecanal (4.7%), 12,15-octadecatrienoicacid, ethylester, (Z,Z,Z)-9 (4.2%), α-eudesmol (3.5%), terpinen-4-ol (3.3%), and palmitic acid (3.2%). The antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. Then, the α-glucose inhibitory activity of the essential oil was analyzed. We investigated the effects of this plant on NO production and cell viability in H₂O₂–induced oxidative stress HUVCEs. The results showed that the QEO had significant antioxidant activity and α-glucose inhibitory effect. Furthermore, the results revealed that QEO could protect HUVECs from oxidative stress and effectively inhibited NO production in that condition. To summarize, the results of this study demonstrated the excellent cellular and antioxidant activity of QEO, and it has potential biological significance in the treatment of cardiovascular diseases.