On solving the access network bottleneck problem (usually known as the last mile problem), Ethernet passive optical network (EPON) is paid a great many attentions. Many works have been done on TDMA-based EPON system. Architecture of a WDM-based EPON system is proposed in this paper. The proposed system consists of one OLT, 1:32 Splitter/combiner, 32 ONUs and a Network Management System (NMS). The OLT includes a Service Node Interface (SNI), an Ethernet switch, an ODN Interface and a Network Management agent, while the ONU includes a User Side Interface (USI), an Ethernet Frame Forwarding, an ODN Interface and a Network Management agent. The downstream data are broadcast from the OLT to all ONUs with 1.25Gbps of line speed. Each ONU send the upstream data encapsulated in Ethernet frames up to OLT with specific wavelength and the 125Mbps of line speed. The upstream signals from all ONUs are aggregated to one fiber by the 1:32 combiner. When the aggregated stream arrives at the OLT, it is de-multiplexed and converted into 32 pairs of signals for more processing. As a result, all ONUs can send data to the OLT simultaneously. Experimental results show that our WDM-based EPON system works well.