A series of coumarin oxime esters were synthesized by two-step reaction with substituted 3-acetyl/butyryl coumarins as the raw material. The reaction of compound 3a was carried out as template reaction, and the effects of the solvent and temperature on the yield of 3a was investigated. The results showed that the yield of the product was the highest when the reaction temperature was 60 ℃ with tetrahydrofuran as solvent. Eleven coumarin oxime esters with different substituent groups were synthesized in 67% ～ 92% yields under the above-mentioned reaction conditions. The struxtures of target compounds have been confirmed by IR, NMR and X-ray crystal diffraction.