Polyaspartic Acid/3-Amino-4-hydroxybenzenesulfonic acid Graft Copolymer (denoted as PASP/3A4HBSA) was synthesized via the reaction of 3-Amino-4-hydroxybenzenesulfonic(3A4HBSA) and polysuccinimide (PSI). The obtained graft copolymer (PASP/3A4HBSA) was characterized by FTIR and 1HNMR. The static scale inhibition method was used to evaluate the scale inhibition behavior of PASP/3A4HBSA and PASP against calcium carbonate. The experimental results showed that: Under the condition of single variable experiment, PASP/3A4HBSA possessed the best scale inhibition property against CaCO3. Inhibition efficiency of PASP/3A4HBSA reached 92.7%, but that of PASP was only 77.1% when the dosage was 100 mg/L in the experiment at 70℃, 24h, pH=7. The scale surface structure and phase structure before and after treatment were characterized by SEM and XRD,Further analysis of the scale inhibition mechanism of the scale inhibitor against CaCO3 was analyzed by FTIR. And it was found that the scale inhibition was mainly caused by lattice distortion of CaCO3, complexation of the scale inhibitor and Ca2+．