A fixing device for fixing a display card on a circuit board, includes a backplane and a support bracket. The backplane includes a substrate plate, and a first engaging part. The substrate plate is fixed on the display card. The first engaging part is disposed on the substrate plate. The support bracket includes at least one support leg and a second engaging part. The support leg includes a first end and a second end. The first end is connected with the circuit board. The second engaging part is connected with the second end and engaged with the first engaging part.