2-Ethylbenzoxazole was synthesized using 2-aminophenol and propionic acid as the reagents and polyphosphoric acid (PPA) as the catalyst assisted with microwave and ultrasonic wave. The influences of mole ratio of catalyst to reactant, reaction temperature, and reaction time were investigated. The optimum technology found was microwave power 800W, ultrasonic wave power 800W, the mole ratio of propionic acid to 2-aminophenol in 55∶1, the mole ratio of PPA to 2-aminophenol in 052∶1, reaction temperature 130℃, and reaction time 15 min. After extracted and distilled in vacuum, the concentration of product of 2-ethylbenzoxazole reached to 9978% with the yield of 4796 %. Compared to 2-methylbenzoxazole, organoleptic characteristics of 2-ethylbenzoxazole was significantly different, which smelled green, salty, sweet, and cool. The structure of 2-ethylbenzoxazole was confirmed by IR, MS and 1H-NMR.