This invention relates to a kind of water heater water discharging device and the water heater using this device. The water-discharging device includes water discharging pipe floating device and its controlling mechanism. The floating device includes the floater setting in the heat conserving water tank. The upside of floater is hollow. The upside of the hollowness assembles with the electromagnet and spring that have the controlling mechanism. One end of the spring sets on the top of the floater, the other end connects to section of iron pipe of the downside of floater hollowness. The said spring ensures the spout of the said water-discharging pipe is below the water surface of heat conserving water tank. A water-discharging pipe, which has matched diameter with the said iron pipe, is inner sleeved on the iron pipe. The other spout of the water-discharging pipe connects to water discharging valve through heat conserving water tank. The controlling switch of the said electromagnet is arranged at the conveniently operational position of heat conserving water tank.