The invention provides a multifunctional gun type water-system fire extinguisher. According to the multifunctional gun type water-system fire extinguisher, a spraying linkage mechanism is driven by pulling a trigger to press a spraying head, and a water-system fire extinguishing agent is sprayed out through a nozzle for fire extinguishing through driving gas between a binary bag and a cylinder wall. The multifunctional gun type water-system fire extinguisher is easy and convenient to operate, high in fire extinguishing efficiency, convenient to carry, safe, reliable, small and exquisite in structure and novel in appearance and is fire-fighting equipment which is quite popular to millions of families; a traditional fire extinguishing way is changed, and the fire extinguisher can be widely used for extinguishing A type fires, B type fires, E type fires and F type fires and suitable for extinguishing initial-stage fires in the target places such as residences, markets, meeting places, high-rise buildings, public places and vehicles.