The invention discloses a gas water heater. The gas water heater comprises a shell, a combustor, heat exchangers, a water inlet pipe, a water outlet pipe and a cooling device. A containing cavity is defined in the shell. The combustor is arranged in the containing cavity, and a combustion chamber is defined in the combustor. The heat exchangers are arranged in the combustion chamber. A cold water inlet end is formed at one end of the water inlet pipe, and the other end of the water inlet pipe communicates with the heat exchangers. One end of the water outlet pipe communicates with the heat exchangers, and a hot water outlet end is formed at the other end of the water outlet pipe. The cooling device is arranged in the combustion chamber so as to reduce the temperature in the combustion chamber. According to the gas water heater in the embodiment, the structure is simple, the cooling device is convenient to install, and the production cost is low; and in the work process, emission of nitric oxide can be effectively reduced, and damage to the environment is reduced.