An electric dust-proof device includes a base seat, a driving mechanism, and a dust-proof cover. The driving mechanism is disposed on the base seat, and includes a power unit, and a drive unit. The drive unit includes a sliding seat driven by the power unit, a pair of first and second pushing portions disposed on the sliding seat and spaced apart from each other, and a guiding assembly for guiding reciprocal movement of the sliding seat along a direction. The dust-proof cover is disposed pivotally on the base seat, and has an engaging portion disposed between the first and second pushing portions, and a cover plate portion connected to the engaging portion. The first and second pushing portions cooperate to move the dust-proof cover between an open position and a close position as a result of the reciprocal movement of the sliding seat.