The invention provides a sectional type water purification treating agent, wherein, a first-phase treating agent comprises potassium permanganate, iodine or hydrogen peroxide; a second-phase treating agent comprises sodium hydroxide, sodium carbonate and sodium hyposulfite; and a third-phase treating agent comprises crystallization aluminium chloride or polyaluminium chloride, citric acid and vitamin C. According to the components and the proportion, the three phases are adopted for treating water, and depositing suspended matter, antisepsis and sterilization can be carried out effectively; after drinking water is treated by the used agent, the drinking water is not only harmless to human body, but also beneficial to human health.