A series-connected fan frame module includes a plurality of frames, an engaging assembly and an anti-rotation assembly. The frames are arranged in series. The engaging assembly is arranged on each of the frames to couple the frames in series. The anti-rotation assembly is arranged on each of the frames and includes at least one position-fixing member and at least one blocking member arranged on portions of adjacent two of the frames where the adjacent two of the frames are coupled together. The at least one position-fixing member is engaged with the at least one blocking member to prevent relative radial rotation between the adjacent two of the frames.