The invention discloses a preparation method of sintered bricks, and specifically relates to a method used for preparing sintered bricks with Friedel's salt. The method comprises following steps: Friedel's salt is fully mixed with 100% basis clay according to a ratio, and the sintered bricks are prepared via traditional clay sintered brick technology. According to the method, Friedel's salt is used for preparing the sintered bricks, and is recycled via sintering processing technology, so that complete and reasonable reutilization of Friedel's salt is realized, wastes are changed into valuables, application amount of clay is reduced, and land resources are protected. Cracks on green bricks prepared via the method are not caused by direct exposure under the blazing sun, and deformation is not easily caused; accessory materials are saved, and a shade-shed is unnecessary; production cost is reduced; with the presence of calcium hydrate, natural drying time of the green bricks of the Friedel's salt sintered bricks ranges from 7 to 8 days, while natural drying time of common clay bricks is about 25 days, so that natural drying period of green bricks is shortened obviously, and production efficiency is increased effectively.