Abstract: Glyceryl monostearate was synthesized by a method of group protection. The optimum conditions for the synthesis were found through orthogonal experiments as：petroleum ether is 120 (mL/molGT)，the molar ratio of glycerol∶ acetone ∶stearic acid is 1∶1.5∶0.7，the mass of catalyst is 5% of glycerol. The elemental analysis and IR spectrogram of the product were identical with the target product. Then the product was mixed with high-level fatty alcohol so as to develop a water-based emulsion non-silicon defoamer. A comparative study on the technical specifications showed that this defoamer is suitable for papermaking and coating process.