Abstract: A modular circuit board that can quickly replace and assemble a port, comprises a first circuit board, at least one second circuit board connected to the first circuit board, at least one connecting post disposed between the first and second circuit boards, and at least one connecting component electrically connected to the first circuit board and the second circuit board; if the modular circuit board needs to replace different ports, it is only need to disassemble the connection post and replace the second circuit board of the second signal port, which not only can reduce the cost of production, and replacement and assembly is more convenient.