The present invention provides an electric dental floss stretching device, which comprises a handle, a fixing tube, and a support member, wherein the handle comprises a vibrating seat, a support section connected to the vibrating seat, and a vibration assembly fixedly equipped to the vibrating seat. The fixing tube fits around the vibrating seat. The fixing tube comprises a projecting barb. The support member comprises a coupling section that has a shape corresponding to the internal cross-sectional shape of the fixing tube and a stretching frame that is connected to the coupling section and has two ends diverging in opposition to each other and comprising two receiving slots. The floss ring is set in the two receiving slots and on the barb, and the vibrating seat is rotated to make the support section extend in the threading direction to expand and stretch the floss ring. Rotating the vibrating seat in an opposite direction will release the floss ring for easy removal of used flosses. The cost of replacing floss ring is relatively low and environment protective and hygiene.本發明提供一種電動牙線撐張器,其包括一握把、一固定管以及一頂撐件,其中,該握把包括一震動座、一連接於該震動座的頂撐部以及一固設於該震動座的震動組件,該固定管套設於該震動座,該固定管包括一凸設的勾部,該頂撐件包括一形狀與該固定管內截面形狀相匹配的結合部,以及一連接於該結合部且兩端背向撐開並包括兩嵌槽的撐張架,將牙線圈架設於兩該嵌槽以及該勾部,並旋轉該震動座帶動該頂撐部沿著螺紋方向伸長並撐開牙線圈,而將該震動座反向旋轉時可鬆開牙線圈,方便取下使用過的牙線圈,替換牙線圈的成本較低且相當地環保與衛生。10‧‧‧握把11‧‧‧震動座15‧‧‧端蓋20‧‧‧固定管30‧‧‧頂撐件31‧‧‧結合部32‧‧‧撐張架40‧‧‧拋棄式牙線圈41‧‧‧手握部
