The invention discloses an electric handheld water-system fire extinguisher. The fire extinguisher comprises a casing, a built-in liquid storage system, an electromechanical workshop and a terminal injection device, wherein the built-in liquid storage system comprises a liquid storage barrel, micro float valves and an anti-overflow air inlet device; the micro float valves are respectively fixed at the front end and the back end of the bottom of the liquid storage barrel; the electromechanical workshop comprises a chargeable lithium battery, a (DC) direct current motor and a diaphragm pump; the DC motor is connected with the diaphragm pump and drives the diaphragm pump. Through the adoption of the manner, the electric handheld water-system fire extinguisher disclosed by the invention has the advantages of scientific structure, novel appearance, reasonable configuration, advanced function, lightness, flexibility, simplicity in operation, high extinguishing efficiency, safety, reliability, economy, practicability and the like, and has a broad market prospect of the popularization of electric handheld water-system fire extinguishers.