The influence of different reaction conditions on the synthesis of acetylsalicylic acid was discussed, in the presence of salicylic acid and acetic anhydride as raw materials, and the deep eutectic solvent of choline choline-oxalic acid as reaction medium and catalyst. The results show that the yield of acetylsalicylic acid could reach 93%, under the conditions of reaction temperature 75℃, molar ratio of salicylic acid to acetic anhydride 1:2.5, reaction time 40 min, amount of choline choline-oxalic acid 1.2 g. This catalytic system offers some advantages, such as low cost, simple preparation, easy recyclability and good biocompatibility, which meets the development requirements of green chemical industry and clean production, and possesses broad development prospect.