Method and device for adjusting water quality and water purifier

The embodiment of the invention provides a method and device for adjusting water quality and a water purifier. The method and device are applied to the water purifier. The water purifier comprises electric desalting equipment used for purifying raw water. The method comprises the following steps: acquiring a first total dissolved solid value of raw water input into the electric desalting equipment; under the condition that the first total dissolved solid value is greater than the target total dissolved solid value, determining a working voltage for controlling the electric desalting equipment to operate according to the first total dissolved solid value and the target total dissolved solid value; applying the working voltage to the electric desalting equipment so as to desalt the raw water and output purified water; acquiring a second total dissolved solid value of the purified water; and adjusting the working voltage through PID feedback control according to the difference between the second total dissolved