The invention discloses an acid-cleaning inhibiter for cleaning a boiler and a use method thereof. The acid-cleaning inhibiter comprises the following components by weight percent: 2.0%-10.0% of acid liquor, 0.08-0.25% of urotropine, 0.04-0.15% of dimethylbenzene thiourea or thiourea, 0.01-0.05% of thiocyanate, 0.03-0.12% of dodecyl-cetyl phenmethyl chloride or bromide, 0.05-0.12% of a surface active agent and the balance of water. Acids suitable for the acid-cleaning inhibiter include hydrochloric acid, citric acid, sulphuric acid, hydrofluoric acid, aminosulfonic acid and phosphoric acid, which are suitable for boiler steel, mild steel, alloy steel and steam steel. The inhibition effect of the invention is over 98% with less toxicity under the boiler chemical cleaning condition, the value of LD50 (orally taken by mice) is 5.74 g / kg. The invention can be stored for 2 years, resistant Fe<3+> ion is 800 mg / kg in the acid cleaning. The preparation method has simple steps, easily obtained raw materials and convention operation.