The invention discloses a built-up synergetic class-A / B water extinguishing agent series. Class-A fires caused by solid substances (such as woods, cottons, wools, linens, paper) and products thereof and class-B fires caused by liquid or melted solids such as gasoline, kerosene, diesel oil, crude oil, methanol, ethanol, asphalt, paraffin waxes and the like can be put out rapidly through the functions such as heat absorption and cooling, diluting and smothering, insulating and covering, suppressing and blocking combustion chains, and the like which are synergetically performed by various extinguishing functional components, and a high-temperature-resistant thermal-insulation and fire-retarding covering layer is formed on the surface of an inflammable matter by various after-combustion functional components so as to achieve the effect of after-combustion resistance. Because the class A / B fires relate to multiple occasions of daily life and production activities, the extinguishing agent disclosed by the invention can be used in the fields of home fire prevention and extinguishing, urban architecture fire prevention and extinguishing, oil depot and gasoline station fire prevention and extinguishing, vehicle and ship fire prevention and extinguishing, forest and grassland fire prevention and extinguishing, mine fire prevention and extinguishing, confined spaces (such as civil air-defense architectures) fire prevention and extinguishing.