EPA Standard is a system specification that was proposed by China to improve industrial ethernet real-time communication performance. On the basis of introduction of the communications protocol model, the modular design of the application layer and the communications scheduling entity of the communications protocol is described, and the task of the protocol stack is divided in detailed. In the design process, the hard real-time and memory utilization of the μclinux system are key consideration. The test results show that the communication protocol stack can work properly and it achieves better results.