The invention provides a constant-temperature water-feeding device for feeding pigs. The constant-temperature water-feeding device comprises a water storage tank, an electric heating pipe, a temperature probe, a temperature controller, a water outlet pipe and a water-feeding device body, wherein the water outlet pipe is connected with the water storage tank, and the water-feeding device body is installed at the free tail end of the water outlet pipe. An electromagnetic valve for controlling water flow to be connected or disconnected is arranged on the water outlet pipe, the electric heating pipe is inserted into the water storage tank, one end of the temperature probe is installed inside the water storage tank to detect the actual water temperature of water inside the water storage tank, the temperature controller comprises a setting module and a controlling module connected with the setting module, the setting module is used for setting a preset water temperature value, the controlling module is connected with the electromagnetic valve, the electric heating pipe and the temperature probe and used for comparing the actual water temperature with the preset water temperature value, when the actual water temperature is lower than the preset water temperature value, the electromagnetic valve is switched off, the electric heating pipe is made to carry out heating, and when the actual water temperature is equal to the preset water temperature value, the electromagnetic valve is switched on to turn off the electric heating pipe. The constant-temperature water-feeding device for feeding the pigs can provide feeding hot water suitable for the pigs.