IEC 61850 based IEDs have been widely used in smart substation. To support simple and efficient engineering configuration, the IED needs an easy accessible configuration query and edit interface, where WEB is a suitable option. Taking digital ERTU as an example, a Web based configuration software including a CGI procedure combining a configuration document and a mapping table, is developed based on Linux embedded OS, which can be reached by engineering work station, or a PC, or a remote work station, to fulfill the configuration work and generate the ICD model documents as well as the device operation parameter documents by interconnection with the substation Ethernet. The new type ERTU with such property has been operated in a 110kV substation in Zhejiang.