Phosphono Scale Inhibitor (PMAAAP) was synthesized through polymerization reaction using maleic anhydride, acrylic acid and sodium hypophosphite as raw materials. The scale inhibition performance of PMAAAP（Phosphono Maleic Anhydride Acrylic Acid Polymer, PMAAAP） under different conditions was investigated. The crystal structure of calcium precipitation was analyzed by XRD and shape characteristic of calcium precipitation was revealed by SEM. The result showed that the maxium calcium carbonate scale inhibition rate is 100% and the maxium calcium phosphate scale inhibition rate is 60.87% under the conditions of dosage is 25 mg/L, pH is 8 and water temperature from 30℃ to 45℃. XRD revealed that the Calcite structure in Calcium carbonate crystal decreased and the unstable vaterite structure appeared. SEM revealed that shape characteristic of calcium carbonate present amorphous. Determination the solution conductivity showed PMAAAP obviously inhibit the formation of calcium carbonate deposits. PMAAAP as an efficient low phosphorus scale inhibitor could be used in industrial cooling water system.