3-Thiazoline is a kind of heterocycle flavor compound containing sulfur and nitrogen. Six 4-methyl-3-thiazoline flavor compounds, including 4-methyl-3-thiazoline, 2,4-dimethyl-3- thiazoline, 2-ethyl-4-methyl-3-thiazoline, 2-isopropyl-4- methyl-3-thiazoline, 2- propyl-4- methyl-3-thiazoline and 2- butyl-4- methyl-3-thiazoline, were synthesized by applying fatty aldehydes, 2,5-dimethyl-2,5-dihydroxy-1,4-dithiane and aqueous ammonia as the raw materials and water or ethanol as solvent in this paper; their yields were 50%-91%. Six compounds were identified by mass spectra, 1H NMR and 13C NMR, followed by evaluating their odor characteristics and measuring their retention indices (RI) on two capillary columns with different polarities. The results indicated that six odorants had roast, nutty and burnt odor, and the RI ranges on HP-INNOWAX column and HP-5MS column were 1398-1686 and 938-1253, respectively. The results obtained had important referenceSvalueSforSmanufacturing, applying and identifying 4-methyl-3-thiazoline flavor compounds.