The utility model belongs to the technical field of an ultracapacitor system, involve an ultracapacitor system's priming device, include: the real empty room that is connected with ultracapacitor system's notes liquid mouth, through connecting pipe and the notes liquid ration room that real empty room is connected, be provided with on the connecting pipe and annotate the liquid switch, annotate the quantitative room of liquid and communicate the feed liquor respectively and manages and the breather pipe, the utility model discloses the liquid measure is annotated in control that can be accurate, improves ultracapacitor system's uniformity, and it is fast to annotate liquid.