In order to improve the comprehensive scale and corrosion inhibition performance of polyepoxysuccinic acid (PESA) and expand its application range, 2-aminoethylsulfonic acid (SEA) was introduced into PESA molecule to synthesize a polyepoxysuccinic acid derivative (SEA-PESA) and applied in seawater environment. SEA-PESA was synthesized by condensation of PESA and SEA, and the structure of SEA-PESA was characterized by Fourier-infrared spectroscopy and 1HNMR. Comprehensive property of scale and corrosion inhibition were studied on SEA-PESA and its quaternary formulation in natural seawater. In seawater environment, when SEA-PESA concentration is 160 mg/L, and the corrosion inhibition efficiencies of Q235 carbon steel is 61.82%, while that of PESA is only 52.17%. The corrosion inhibition rates of the quaternary formulations of PESA and SEA-PESA were 88.87% and 96.99%, respectively, and the corrosion rates were 0.06 552 mm/a and 0.017 72 mm/a. The corrosion inhibition effect of the quaternary formulations of SEA-PESA was better than PESA’s, which better met the requirements of national standards. SEA-PESA quaternary formulation is an anodic corrosion inhibitor, which mainly inhibits the anode. It also showed good scale inhibition performance in seawater, and the scale inhibition rate reached 100% at the dosage of 10 mg/L. This study confirmed the potential of SEA-PESA for corrosion inhibition and scaling inhibition in cooling systems and thermal desalination processes, especially in seawater environment, and has a broad application prospect.