This invention relates to the field of wall leveling technology, specifically to a leveling device for plastering ALC board surfaces. The device includes a scraper, with a flatness detection device movably connected to the outer wall of the scraper. A mounting frame is fixedly connected to the outer wall of the scraper, and a connecting rod is rotatably connected to the bottom of the mounting frame. A slide block is rotatably connected to the lower end of the connecting rod, and an inner slide rail is movably connected to the bottom of the slide block, allowing the slide block to slide along the inner slide rail. This invention utilizes the connecting rod, whose length remains constant. When the telescopic push rod extends and the inner slide rail approaches the wall, the scraper is positioned at the upper part of the wall; when the inner slide rail moves away from the wall, the scraper is positioned at the lower part. Due to the connecting rod, the mounting frame and slide block remain parallel under the constraint of two support bars. The scraper is fixedly connected to the mounting frame, thus maintaining a vertical position, enabling the scraper to level various parts of the wall.
