A card edge connector assembly is disclosed. The card edge connector assembly includes an insulating housing, a first circuit board, a line transmission device, and a covering body. A plurality of first terminals and second terminals are inserted into the insulating housing. The first terminals and the second terminals are electrically connected to the line transmission device via the first circuit board. The first terminals are above the second terminals and mating portions of the first terminals and the second terminals stretch into a plug space of the insulating housing. In this way, the plug space can be used for the second circuit board to plug in such that the first terminals and the second terminals are electrically connected to the second circuit board.