The invention relates to the field of clearing, cleaning water scales and other stubborn scales. The invention discloses a detergent which comprises the following main active components in parts by weight: 1-5 parts of nonionic surfactant, 0.5-10 parts of anionic surfactant, 0.5-5 parts of ampholytic surfactant, 2-50 parts of methylsulfonic acid, 1-5 parts of hydroxy ethylidene di-phosphonic acid and 0.3-1.0 part of corrosion inhibitor. The detergent can effectively remove the water scales, rusty scales, tea scales, oil scales, dust scales and urine scales on daily life appliances of people, has the effects of removing the scales, cleaning, sterilizing, removing odor and the like, and can be used for hard surfaces of plastic, metal, stainless steel, porcelain and other products.