Abstract: A green scale inhibitor polyepoxysuccinic acid(PESA) was synthesized from maleic anhydride in one step, and was characterized with IR and ¹³C NMR.The effects of PESA on CaCO₃ scale diameter and scale shape were investigated by size distribution measurement and SEM respectively.The dynamics of scaling process was studied, and the mechanism of scale inhibition was discussed.The results showed that PESA had high performance of scale inhibition on both dispersion and lattice distortion of CaCO₃.