The invention discloses an expansion card fixing device, comprising: a "["-shaped bracket, wherein its two arms are symmetrically provided with a pair of slides and have a pair of first connecting parts symmetrically formed on them, and the bottom side is fixedly connected with a back plate which is equipped with at least one expansion card slot; and a "["-shaped expansion card compressing member, wherein its two arms symmetrically form a pair of sliding blocks and a pair of second connecting parts, the bottom side extends laterally to form at least one shrapnel. Each sliding block is embedded in a slide and can slide along the slide. When the sliding blocks are in a first end of the slides, the second connecting parts and the first connecting parts are positioned correspondingly and can be connected in a nested way, the shrapnel abuts against an expansion card inserted in the expansion card slot so as to apply a compressing force pointing in the direction of the back plate to the expansion card, and when the sliding blocks are in a second end of the slides, the shrapnel is separated from the expansion card, without overlapping. The expansion card fixing device provided by the invention improves assembly and maintenance convenience of the expansion card.