The present invention relates to the technical field of refrigeration devices, and more particularly, relates to a preservation and sterilization device for refrigerator and a method for controlling the same. A preservation and sterilization device for refrigerator comprises: an electrical control panel, a DC high-voltage power supply, and an ion generator that are sequentially coupled, the ion generator comprising positive and negative ion discharge electrodes; wherein when an input voltage of the ion generator is constant, a DC high voltage output by the ion generator is regulatable to respectively obtain high voltages required for preservation and sterilization. By means of adjusting the design circuit of the DC high-voltage power supply in the ion generator to implement switchover of the output voltage of the ion generator, the present invention solves the technical problem that when the input voltage is constant, the ion generator of a conventional refrigerator only outputs a fixed DC high voltage, which merely singly implements the preservation function or the sterilization function. By means of smart control of the refrigerator, the present invention implements integration of the preservation function and the sterilization function, and achieves the technical effect of concurrently implementing the preservation function and the sterilization function in the refrigeration compartment of the refrigerator by using the same device.