The invention relates to a gas water heater with a water cutoff temperature rise prevention function. The gas water heater comprises a heat exchanger, a main controller, a cold water temperature measuring component, a cold water flow rate sensor, a hot water proportional valve, a water outlet temperature measuring component, a cold water inlet pipe and a hot water outlet pipe, wherein a cold water pipe and a hot water pipe are arranged on the heat exchanger, and the cold water flow rate sensor is arranged on the cold water pipe. The gas water heater has the main technical characteristic that the gas water heater also comprises a bypass pipe, a bypass water proportional valve, a bypass water flow rate sensor, a hot water temperature measuring component and a water cutoff temperature rise controller, wherein the bypass pipe is communicated with the cold water pipe and the hot water pipe, the bypass water proportional valve and the bypass water flow rate sensor are arranged on the bypass pipe, the hot water temperature measuring component is arranged on the hot water pipe, the cold water temperature measuring component is arranged on the cold water pipe or the bypass pipe, and the water cutoff temperature rise controller is electrically connected with the bypass water proportional value, the bypass water flow rate sensor, the hot water temperature measuring component and the main controller. The gas water heater has the characteristics that the water cutoff temperature rise of the gas water heater can be effectively avoided, the outlet water temperature is vey stable, the use comfort is improved, the harm of residual hot water to the health of users is avoided, and the like.