To improve traditional L-aspartic acid polymerization in organic liquids,Polyaspartic acid(PASP) was synthesized in the medium of AlCl3-Et3NHCl ionic liquids by polymerization using L-aspartic acid as a raw material.The influence of composition of ionic liquids and reaction conditions on PASP weight average molecular weight and inhibiting effect on calcium carbonate were studied.The characteristics of the infrared spectrum of the product were analyzed.The results show that the obtained product in the medium of AlCl3-Et3NHCl ionic liquids is PASP,the molecular weight of PASP is between 1 000-5 000,and the optimal conditions of polymeric reaction are that the molar ratio of anhydrous aluminum chloride and triethylamine hydrochloride is 2.2∶1,reaction temperature is 220 ℃,concentration of L-aspartic is 0.2 g/mL and reaction time is 2.0 h.Under the above conditions,its molecular weight is 4 750,the scale inhibition rate to calcium carbonate reaches to 93.8% and it is increased by 5% compared with the traditional liquid-phase polymerization process.The PASP can be synthesized in ionic liquids.