Wireless sensor networks (WSNs) have become widely used because of their low cost and low power consumption. With the IPv6 Low-power Wireless Personal Area Network (6LoWPAN) standard proposed by Internet Engineering Task Force (IETF), WSN can be seamlessly integrated with Internet devices running IPv6. With 6LoWPAN, it will be easy to manage a lot of sensors via the Internet. This thesis illustrates the design and implementation of an enhanced network management system for 6LoWPAN-based WSNs. Through the simple network management protocol (SNMP) and an event-driven mechanism, the system can help users to manage a large number of sensor devices efficiently.