Stacked serial port and RJ45 network port expansion mainboard

The utility model discloses a stacked serial port and RJ45 network port expansion mainboard. The stacked serial port and RJ45 network port expansion mainboard comprises an embedded PCM mainboard, an interface board and a USB-to-RJ45 network port concentrator, the embedded PCM main board and the interface board are stacked; the embedded PCM main board comprises a USB3.0 interface and a USB2.0 interface, and the USB3.0 interface is connected with the USB-to-RJ45 network port concentrator; the interface board comprises a USB concentrator, a plurality of USB to serial port modules and a plurality of first serial ports, the combining end of the USB concentrator is connected with the USB2.0 interface, the branching ends of the USB concentrator are connected with the first ends of the USB to serial port modules in a one-to-one correspondence mode, and the second ends of the USB to serial port modules are connected with the first serial ports in a one-to-one correspondence mode. The mainboard is expanded by adopting