The invention discloses a water additive agent for fire fighting. The water additive agent for fire fighting is prepared via mixing of a fire extinguishing functional component with an anti-aftercombustion functional component at a certain ratio; the fire extinguishing functional component is composed of a cooling functional component, a covering isolating functional component, a diluting
oxygen-isolating functional component, a
combustion chain blocking functional component, and an emulsifying agent of the
combustion chain blocking functional component; the anti-aftercombustion functional component is composed of a nano thermal-isolation fire-proof
flame-resistant material, a suspension dispersive agent of the nano thermal-isolation fire-proof
flame-resistant material, a water-soluble inorganic
flame retardant, a
radiation absorption material, and a film-forming agent; and the covering isolating functional component is composed of a foaming surfactant with high foamability, a
fluorine series surfactant, a
silicon series surfactant, and a foam stabilizing accessory ingredient. The water additive agent possesses excellent fire extinguishment effect on
fire disasters caused by wood, paper, cotton products,
hay,
coal, rubber, nonpolar liquid (such as
gasoline and
kerosene), polar liquid (such as methyl
alcohol and ethyl
alcohol), and chemical materials such as
magnesium and
titanium.