Cinnamic acid was synthesized by Perkin reaction in anhydrous potassium carbonate as catalyst,ionic liquid as solvent.The optimal process conditions were obtained as follows:n(PhCHO):n(Ac2O):n(K2CO3)=1∶1.2∶1.1,and refluence time was 2h when the refluence temperature was 160℃.The yield of cinnamic acid could reach 80.8%.