Objective This paper aims to investigate the effects of microwave and roasting pretreatment methods on volatile compounds and active ingredients in flaxseed oil.Methods Flaxseeds were pretreated by microwave (720 W, 2~8 min) and roasting (140~200 ℃, 30 min), and then flaxseed oil was prepared by cold pressing. Using untreated cold-pressed flaxseed oil as a control, the differences in volatile compounds were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and an electronic nose. Additionally, the contents of tocopherols, phytosterols, and total phenolics were determined.Results A total of 72 volatile compounds are identified by HS-GC-IMS analysis, including aldehydes (20 types), ketones (8 types), and heterocyclic compounds (14 types). Cold-pressed flaxseed oil is dominated by alcohols (53.11%) and aldehydes (20.08%), conferring grassy and fruity aromas. After microwave and roasting treatments, heterocyclic compounds and ketones increase significantly (with maximum increases of 16.71% and 11.22%, respectively). Among them, the content of heterocyclic compounds in flaxseed oil roasted at 200 ℃ (21.37%) is 4.6 times that of cold-pressed oil, significantly enhancing the nutty and roasted aromas. Different pretreated oil samples can be effectively distinguished by the electronic nose. Principal component analysis (PCA) shows a significant separation between the cold-pressed group and heat-treated groups (microwave and roasting), and roasting exerts a greater impact on the aroma than microwave treatment. Flaxseed oil prepared after moderate microwave and roasting treatments is rich in higher levels of γ-tocopherol, phytosterols, and total phenolics; however, excessive microwave or roasting is detrimental to the retention of active ingredients.Conclusion Pretreatment using moderate-low temperature roasting (160~180 ℃) or moderate-short duration microwave (4~6 min) not only improves the flavor quality but also reduces the loss of active ingredients, which is suitable for flaxseed pressing processing.