To realize the functions of communications processor module, an embedded TCP/IP protocol stack was proposed based on the uC/OS-II real-time operating system and the hardware platform of ARM7 kernel, which can support multi-threaded real time application by transplanting the LwIP to ARM development platform. On the communication application layer, the Modbus frames was embedded to the TCP frames, and the Modbus/TCP protocol communication structure model was analyzed, in order to ultimately achieve the embedded Modbus/TCP communication protocol simply and reliably. The results indicated that the Modbus/TCP data transfer between client and server was realized stably and effectively by combining with Modbus/TCP protocol and establishing several thread functions.