Abstract: An etching system (3) includes an etching chamber (31), an etchant solution tank (32) connected with the etching chamber, a heater (34) set in the tank, and a deionized water (DIW) adding device. The DIW adding device includes a DIW feeding pipe (36) having a first timer (361), and a clean dry air (CDA) feeding pipe (35) having a second timer (351). The DIW and CDA feeding pipes combine into a main pipe (37) that is connected with the etching chamber. A portion of the DIW feeding pipe is set in the tank and heated by the heater. The temperature of the DIW fed into the etching chamber and the temperature of the etchant solution pumped into the etching chamber are same. Thus when the DIW is fed into the etching chamber, the temperature of the etching chamber does not fluctuate, which can maintain the quality of the etching process.