Abstract: Because of the actuality that the wireless sensor network (WSN) can not be directly accessed into the Ethernet, this article proposes the conceptions of eWSN switch, EI-eWSN switch and logical net node according to the operation principle of Ethernet switch, and designs and achieves the WSN system based on the TCP/IP protocol.The Ethernet address is applied to the wireless node in this WSN system, and the data is encapsulated in Ethernet frame format for transmission, the seamless integration of WSN and Ethernet is realized.