The substation intelligent electronic device (IED) of substation on-line monitoring gathers and uploads status information on primary equipment to comprehensive application server and other devices in the station layer using the communication method in compliance with IEC 61850 standard. As the key device of the integrated supervision and control system

the test of its functions is the foundation of the normal operation of the on-line monitoring system. By analyzing the functions of the on-line monitoring IED

the description of functional test cases is given and the automated testing script and testing engine is designed to replace the manual test

which improves the testing efficiency. Finally

by taking the uploading function of oil dissolved gas monitoring data as an example

an automated testing system for on-line monitoring IED is developed and used to conduct an automated testing experiment. The procedures and results of automated testing are also given to verify the correctness and feasibility of this method.