The work aims to synthesize a multifunctional polyepoxysuccinic acid derivative (MEA-PESA) modified by ethanolamine to change the single-functional structure of green scale inhibitor polyepoxysuccinic acid (PESA), thus improving the scale and corrosion inhibition properties of PESA and verifying the mechanism of scale and corrosion inhibition of MEA- PESA. Epoxysuccinic acid (ESA) was obtained from maleic anhydride through cyclic reaction, and then PESA was obtained through polymerization reaction. Finally, MEA-PESA was obtained by condensation of PESA and ethanolamine (MEA). The structures of PESA and MEA-PESA were characterized by FTIR and HNMR. The optimum conditions of MEA-PESA synthesis: the mass ratio of polyepoxysuccinic acid and ethanolamine was 10∶7, the modification temperature was 80 ℃, the modification time was 2 h, and the stirring rate was 1500 r/min. When the concentration of MEA-PESA was 16 mg/L, the resistance of calcium carbonate and calcium phosphate reached 95% and 97% respectively. At 150 mg/L, the corrosion inhibition rate of MEA-PESA was 73%, 12% higher than that of PESA. Scanning electron microscope (SEM) and infrared spectroscopy (FTIR) were used to investigate the crystal pattern of calcium scale. The peak value of calcium scale crystal pattern shifted, and the peak of unstable crystal appeared, while the peak of stable crystal decreased, and the crystal structure in the electron microscope image changed from compact to loose. Corrosion inhibition mechanism of MEA-PESA was studied by electrochemical polarization curve. MEA-PESA was a mixed corrosion inhibitor which mainly inhibited the anode reaction. The corrosion current decreased, but the corrosion potential increased. Under the same scale and corrosion inhibition test conditions, MEA-PESA is better than PESA in inhibiting calcium carbonate, calcium phosphate and corrosion inhibition, which has better application value for expanding the application range of PESA.