Disclosed is an expansion card fixing device. The expansion card fixing device is used for fixing an expansion card and comprises a housing, a circuit board is arranged inside the housing, and the lower edge of the expansion card is inserted into the circuit board; a press assembly is pivotably mounted inside the housing and comprises a press piece made of elastically-deformable soft materials, the press piece comprises a press part and fixing parts arranged on both sides of the press parts, and the distance between the two fixing parts is larger than the width of an upper edge of the expansion card; the upper edge of the expansion card is accommodated between the two fixing parts; the press part is pressed onto the upper edge of the expansion card.