ＡＰＯＮ系统是一种优良的高速、宽带接入解决方案，世界上许多科研机构和通信公司不惜投入巨资进行大规模的研究和开发。本文简述了 ＡＰＯＮ接入系统的网络分层结构、光网络终端的各功能模块。通过对系统的整体分析，确定了光网络终端设计中的核心工作是物理层实现，进而本文提出了物理层芯片的实现途径并给出了整个光网络终端的实现框图。 APON system is an excellent high-speed, broadband access solutions, many of the world’s research institutes and telecommunications companies have invested heavily in large-scale research and development. This article describes the APON access network hierarchy, optical network terminal function modules. Through the overall analysis of the system, it is determined that the core work in the optical network terminal design is to realize the physical layer. In this paper, the ways to implement the physical layer chip and the block diagram of the whole optical network terminal are given.