The technical scheme of the invention is as follows: a water heating machine comprises a housing, a panel, a base plate, a water receiving tray, a water tank, an outer water tank receptacle, a water pump, a heater assembly, a steam discharge pipe, a water outlet hood, a water tank cover, a pipeline, a pilot circuit and a water temperature control system; as seen in the figure, the heater assembly consists of an electric heating tube, a stainless steel tube, a silicon rubber flange, a water inlet chamber, a water outlet chamber, a communicating tube, a water level control tube, a magnetic floating ball, a dry reed pipe and an upper cover; a water inlet, a water outlet, a water return pipe and a floating ball chamber are arranged at the bottom of the water inlet chamber; the water temperature control system comprises a water temperature control button, a pull line, the water level control tube, a seal ring, a tension spring and a microswitch; the water level control tube is arranged in the water return pipe of the water inlet chamber and can slide up and down in the water return pipe; the seal ring is arranged between the lower end of the water level control tube and the water return pipe; and the outer water tank receptacle consists of a housing, a silicone rubber seat, an inner valve and a spring. The water heating machine provided by the invention can provide boiling water within 3-5 seconds; has the advantages of simple structure, high stability and reliability, safety, hygiene, convenience for operation and zero idle power consumption; and is significant in market advantages.