The invention relates to a high-temperature acidification corrosion inhibitor and a preparation method thereof, comprising the following materials: 79.33-87.68 parts of ethanol, 19-21 parts of formic acid, 22.33-24.68 parts of aniline, 31.11-34.39 parts of acetophenone, and 26.13-28.88 parts of formaldehyde , 31.54-34.86 parts of benzyl chloride and 8.55-9.45 parts of propynyl alcohol, place ethanol, formic acid and aniline in the reaction kettle and stir, then add acetophenone into the reaction kettle, and then drop formaldehyde solution into the reaction kettle After adding the formaldehyde solution dropwise, add benzyl chloride into the reactor, lower the temperature of the reactor to room temperature, then add propynyl alcohol and stir. No need to add hydrochloric acid aqueous solution, the water content in the reactor is low, avoiding the hydrolysis of benzyl chloride, which is beneficial to reduce the unit consumption of benzyl chloride in the process of quaternization reaction, before adding formaldehyde dropwise, drop into the reactor The amount of formaldehyde is lower than the reaction molar ratio of synthetic Mannich base, and the formaldehyde is in a state of insufficient amount, which reduces the volatilization of formaldehyde, ensures the health of operators, and is safer.