Scale inhibitor

The invention relates to a scale inhibitor which has a relatively good corrosion and scale inhibition effect and can effectively treat industrial high-mineral-ion wastewater. The scale inhibitor comprises a component A and a component B which are mixed with each other, wherein the component A is hydrolytic polymaleic anhydride (HPMA); the component B is copolymer synthesized by using itaconic acid (IA), 2-acrylamido-2-methyl propyl sulfonic acid (AMPS) and 2-2-acrylamido-2-methyl propyl phosphonic acid (AMPP); in a molecular formula of the copolymer, x, y and z represent mole numbers of IA, AMPS and AMPP respectively, and the ratio of x to y to z is (50.3-70.6) to (11-16) to (33-41); the mass part ratio of the component A to the component B is (4-6) to 1.