A fixing mechanism includes a casing, a bracket structure, and a fixing rod. The bracket structure is disposed at a side of the casing corresponding to an interface card and has a positioning member and a pivot member. The fixing rod is movably disposed on the bracket structure and includes a clamping portion, a hook portion, and a torsion-spring portion. The clamping portion is used for clamping an end of a bending board of the interface card cooperatively with the bracket structure. The hook portion is connected to a first end of the clamping portion for hooking the positioning member when the clamping portion moves to a fixing position. The torsion-spring portion is connected to a second end of the clamping portion and pivotally connected to the pivot member for driving the clamping portion to a releasing position to separate the clamping portion from the end of the bending board.