We employed microfluid technique to synthesize ethyl vanillin by using microfluid technique. The structure of obtained ethyl vanillin was characterized by FTIR. The conditions of reaction temperature, flow velocity and the amount of raw materials were investigated and optimized to produce ethyl vanillin with high yield. The optimized experimental results indicated that using o-ethoxyphenol and chloroform as the main raw materials in the presence of phase-transfer catalyst of triethylamine will induce the Reimer-Tiemann reaction to form ethyl vanillin. The molar ratio was o-ethoxyphenol: chloroform: sodium hydroxide: triethylamine = 1:1.2:4.0:0.025, reaction temperature was 55℃ and flow rate was 6 mL/min. Results revealed that this method had features of short technological process and convenient manipulation. Under the optimal conditions, the yield ratio of ethyl vanillin was up to 82.3%.