A fixing device for use with at least one expansion card in a computer chassis includes a positioning member and a fixing member. One side of the positioning member defines at least one first slot. The fixing member includes a fixing portion and a rotatable portion rotatablely connected to the fixing portion. The fixing portion defines at least one second slot corresponding to the at least one first slot. When the rotatable portion is able to rotate to a position where the at least one first slot face to the at least one second slot, allowing opposite sides of the free end of the at least one expansion card.