Hazelnut oil, extracted from hazelnuts, can be used as a functional food with many nutritional benefits. To completely assess its chemical constituents in hazelnut oil, one main cultivar of a flatEuropean hybrid hazelnut (C. heterophylla Fisch. x C. avellana L.) cv. 'Dawei' was taken as the material, and a new optimized silyl-etherification derivatization was established by being followed with Gas chromatography-mass spectrometry (GC-MS). Meanwhile, an electron spin resonance (ESR) method was used to elucidate the scavenging capacity of free radicals. In result, the filbertone (exclusive marker), 16 fatty acids (8 saturated and 8 unsaturated), 4 sterols and 5 other components were identified at once. Furthermore, hybrid hazelnut oil, filbertone and two sterols that contained in hazelnut oil were used to test the scavenge free radical activities. The results showed that the hybrid hazelnut oil expressed meaningful IC50 values (DPPH: 66.39, hydroxyl: 66.64, alkyl: 118.82 and O-2 : 75.38 mu g/mL). In conclusion, this study selected an effective derivatization method for the chemical IP: 14.98.160.66 On: Fri, 11 Feb 2022 06:38:05 constituents detection, and provided detailed dta, which laid an experimental foundation for quality Copyright: American Scientific Publishers control of a hybrid hazelnut oil. In addition, the free radical scavenging activity was observed, which provided a basis for the development of antioxidant products in hybrid hazelnut oil.