The invention belongs to the technical field of chemical cleaning, and particularly relates to a thin-layer cement scale chemical cleaning agent mainly composed of hydroxyacetic acid. The product is prepared from the following raw materials: hydroxyacetic acid, surfactant, corrosion inhibitor, penetrant, scale inhibitor, colorant and water. After being sprayed on the thin-layer cement scale, the product can quickly penetrate to the inside of the cement scale and initiate chemical reaction to form fluffy substances, thereby lowering the adhesive force of the cement; and after some time, clear water is used for flushing, thereby easily removing the thin-layer cement scale. The product has the characteristics of no toxicity, no harm, small corrosivity for metal equipment and other base materials, small harm to operating personnel and the like, can be widely used for cleaning the cement scale on building wall surfaces, hardened cement scale on experimental equipment, cement stains on daily supplies and the like, and has favorable economic benefits and environmental benefits.