For some special devices only equipped with RS-422 or LVDS serial port without an Ethernet port,the data transparent transmission between the upper computer and they can only be realized by the serial port converter on the market,such as Moxa Uport series USB to serial port converter.This data transparent transmission mode not only has short transmission distance,low efficiency,high cost,but also cannot access the network.To solve these problems,a design scheme of TCP netword-serial data transmittal device based on LwIP is proposed.The data transmittal device uses ZYNQ-7020 SoC as the main control chip to design RS-422 interface circuit and LVDS interface circuit,which realizes the transmittal of network data and RS-422/LVDS serial data.Finally,through the performance test carried out on a certain inspection equipment,it is proved that the serial ports of RS-422 and LVDS of the data transparent transmission equipment can realize the data transparent transmission function without packet loss and error at any rate less than 2 Mb/s,which provides a reliable implementation scheme for the data transparent transmission between the network port and the serial port.