Cooling water treatment agent supplementing system

The utility model discloses a cooling water treating agent supplementing system which comprises a PH sensor, an engine electric control unit and a treating agent supplementing device, the treating agent supplementing device comprises a liquid outlet pipe, the liquid outlet pipe is communicated with a fresh water inlet pipe, a switch unit is arranged on the liquid outlet pipe, and the switch unit is electrically connected with the engine electric control unit; the engine electric control unit is used for controlling the switch unit to be turned on or turned off according to the PH value detected by the PH sensor. During use, the PH sensor detects the PH value of fresh water in real time, converts the PH value into a corresponding electric signal and transmits the electric signal to the engine electric control unit, the engine electric control unit is used for comparing the PH value with a preset limit value, when the PH value exceeds the preset limit value, the switch unit is triggered to be turned on to suppl