Substation configuration description (SCD) plays a critical role in IEC 61850 based smart substations. This paper proposes a solution of smart substation secondary system visualization and intelligent diagnosis based on a complete SCD model, in order to mitigate the issue that the SCD file is difficult to effectively support object-oriented IEC 61850 advanced applications. This solution builds topological relationships among primary, secondary equipment, and network communication using SCD application models. The effectiveness of the proposed solution is validated in a demo platform of a 500 kV smart substation secondary system. This demo system realizes various advanced applications and object-oriented management of smart substation based on the complete SCD model, which will provide reliable technical support for substation operation without human being, dispatching and control integrated, as well as operation and maintenance integrated.