The invention provides a variable optical attenuator. The variable optical attenuator comprises a tube seat, a chip, a driving negative electrode and a driving positive electrode, wherein the tube seat comprises a bottom seat and a base which is positioned on the surface of the bottom seat; the chip is positioned on the surface of the base; the driving negative electrode penetrates through the bottom seat, is electrically connected with the base, and is connected with the negative electrode of the chip through the base and a wire or a bonding pad which is electrically connected with the base; the driving positive electrode is positioned in the base below the chip, and is connected with the positive electrode of the chip through the wire or the bonding pad. The driving positive electrode is not positioned on one side of the chip any longer, but is positioned in the base below the chip, so that the sizes of the tube seat and the base can be reduced, the size of the variable optical attenuator can be reduced accordingly, and the integration level of the variable optical attenuator can be improved.