Based on the communication demand of smart substation, a new kind of communication architecture named EPON+, which is developed on the basis of EPON (Ethernet Passive Optical Network) and has the character of highreliability and fixed latency, is proposed as the desired one to establish the network in substation. Then the type and the quality of service (QoS) of EPON in substation, including the requirement of real-time and reliability, can be defined precisely. To satisfy the QoS, some modifications are made on EPON technology, which go as follows. In the software aspects, not only the manner of register and the bandwidth allocation algorithm are changed, but the “delay-waiting” algorithm also is deployed, so that the packets can be transmitted fast and smoothly. Then with the duplicate configuration in hardware, the reliability of communication can be ensured. Finally, the performance of EPON+ based network is tested in 220 kV Yongning Substation. The results show that EPON+ can meet the requirement of substation, therefore testify the feasibility of deploying EPON+ in substation communication architecture.