Management network plays an important role in the SDH transport system. Adopting the management architecture of CMIP, traditional SDH management network is chiefly a subset of TMN. Although its management ability is powerful, it is complex to implement. Considering not only the SNMP's simplicity and low resource consumption but also the flexible extensibility brought by the application of the extensible agent (AgentX) architecture, a different strategy of the SDH management network based on the SNMP management structure with AgentX is proposed in this paper. The design scheme of AgentX in the system is discussed further.