A method for synthesizing β?hydroxyethyl sulfide by reacting a thiol with ethylene carbonate by an organic acid potassium salt (KA) was reported. The results show that under normal pressure and solvent?free conditions, KOAc, KSAc and HCOOK have higher catalytic activity, and the catalytic activity of multi?organic potassium salt is relatively lower, while CF₃SO₃K and CH₃SO₃K have no catalytic activity. With KOAc as a catalyst, the order of reaction of various thiols is thiophenol>2?mercaptoethanol>hydrazine thiol>normal aliphatic thiol. According to the theory of soft and hard acid and base, the activation mechanism of -S-H by potassium salt was discussed.