The invention relates to the field of water treatment chemicals, in particular to a high-temperature-resistant slow-release scale inhibitor. The high-temperature-resistant slow-release scale inhibitor comprises the following substances in parts by weight: 6-12 parts of a starch substrate, 12-15 parts of acrylic acid, 6-10 parts of 2-acrylamido-2-methylpropane sulfonic acid, 20-25 parts of polyaspartic acid, 5-10 parts of a nitrogen-containing heterocyclic compound composition, 10-15 parts of water-soluble oxidative inorganic metal salt, 5-10 parts of water-soluble inorganic zinc salt, 5-10 parts of homopolycarboxylic acid, 5-10 parts of lignosulfonate, 10-15 parts of sodium polyhydroxy carboxylate, 5-10 parts of a cellulose derivative, 5-8 parts of a composite initiator, 3-6 parts of a dispersed activator and 5-10 parts of an auxiliary corrosion inhibitor. The high-temperature-resistant slow-release scale inhibitor provided by the invention is low in cost, wide in source, friendly to environment, nontoxic and free from secondary pollution; the scale inhibitor is resistant to high temperature, can effectively inhibit the formation of calcium carbonate scales, calcium sulfate scales, barium sulfate scales and calcium phosphate scales in an oilfield pipeline and a boiler, has a good slow release effect on the pipeline and the boiler, and can prolong the service life.