This paper discusses the plug-and-play application scenario of smart substation in dispatching control center, and proposes and realizes a plug-and-play technology of smart substation graphics file in dispatching control center. The technology does not need to maintain the graphics file at the source, only need to obtain substation SCD model, automatically generate substation main wiring diagram. By analyzing the SCD file of the substation, the topology relation of the substation is obtained. The devices are grouped by the depth-first search algorithm in topology relation. Then the objective function of the layout is constructed, and the position of the layout element is adjusted by the global optimization algorithm. Finally, the main wiring diagram of the substation is generated during the iterative optimization process. In order to save the search time, the neighborhood optimization strategy of the global optimization algorithm is improved. The technique of this paper is applied to the automatic generation of the main wiring diagram of 500 kV substation in a province. The results show that this technology can quickly generate the main wiring diagram. This work is supported by National Key Research and Development Program of China (No. 2017YFB0902600); Science and Technology Porject of State Grid Corporation of China (No. SGJS0000DKJS1700840) “Research and Application of Key Technology for Intelligent Dispatching and Security Early-warning of Large Power Grid”.