The invention discloses a water heater capable of displaying the amount of hot water. The water heater comprises an inner container, a water inlet and a water outlet, as well as a heating pipe positioned in the inner container. The water heater further comprises a temperature sensor I arranged at the water inlet of the water heater, a temperature sensor group arranged on the outer surface of the inner container of the water heater and a flow sensor arranged at the water outlet of the water heater; the temperature sensor I, the temperature sensor group and the flow sensor are correspondingly connected with input ends of a microprocessor, the temperature sensor I, the temperature sensor group, the flow sensor and the microprocessor, as well as a display which is linked with the microprocessor constitute a detection and display device of the amount of hot water of the water heater. The invention provides the water heater which can accurately measure the water temperature of the water heater and display the current amount of hot water with the preset temperature in the water heater.