Abstract: The present invention provides a control device for maintaining a chemical mechanical polishing (CMP) machine in a wet mode, the CMP machine comprising a polishing pad, a slurry sprinkler for sprinkling liquid or deionized water, and at least one carrier head, the control device comprising a sensor positioned on the CMP machine for sensing the operational status of the slurry sprinkler and generating a corresponding sensing signal; and a control unit electrically connected to the sensor for measuring the time period over which the slurry sprinkler is closed wherein when the measured time period exceeds a predetermined length, the control unit will either send a warning signal or turn on the slurry sprinkler to sprinkle liquid onto the polishing pad according to a predetermined process so as to maintain the polishing pad in a wet mode.