The invention provides a water boiler which comprises a water tank, a temperature detection module for detecting water temperature in the water tank, a gas pressure detection module for detecting gas pressure of an environment in which the water boiler is positioned, a heating module, and a control module, wherein the control module is connected with the temperature detection module, the gas pressure detection module and the heating module respectively, acquires water boiling point temperature according to the environment gas pressure and controls the heating module according to the water boiling point temperature and the water temperature in the water tank. The water boiler acquires the water boiling point temperature by detecting the current environment gas pressure, so that the heating temperature can be automatically set, and the problems that the conventional water boiler heats the water all the time, the water is boiling all the time and the like are solved; the reliability and the safety of a product are improved, and the electric energy is effectively saved. The invention also provides a control method for the water boiler.