Polyaspartic acid/diethylenetriamine (PASP/DETA) graft copolymer was synthesized by urea, maleic anhydride and diethylenetriamine and its performance was evaluated by the static scale inhibition method. Due to the intramolecular hydrogen bonds of the side chains, the seven-member heterocycles were formed in graft copolymers. The results showed that the graft copolymers possessed improved scale inhibition performance against Ca-3(PO4)(2) compared with PASP. The scale inhibition efficiency was close to 100% against Ca-3(PO4)(2) and CaCO3, when the concentration of PASP/DETA was 15 mg/L and 6 mg/L, respectively. Meanwhile, its scale inhibition performance was studied in different solution pH and temperature. The CaCO3 and Ca-3(PO4)(2) crystal turned into irregular shapes with the introduction of PASP/DETA in the solution, which was observed by scanning electron microscopy.