The invention provides a virtual node-based power grid single line diagram automatic layout method, which comprises the following steps of: reading a power grid topological structure, acquiring all node and line sets, performing first-stage layout on all node lines by applying a first differential evolution algorithm to obtain an initial layout diagram, applying a second differential evolution algorithm to carry out optimized layout of a main region in the second-stage layout, determining the range of a virtual region based on virtual node coordinates, applying a third differential evolution algorithm to carry out layout of the virtual region in the second-stage layout, and carrying out layout in the range of the virtual region corresponding to each virtual node, obtaining the coordinate of each node, and completing the automatic layout of the power grid single line diagram. According to the method, a differential evolution algorithm is applied, a comprehensive layout and routing mode is adopted, a penalty term is introduced into a target function, the problem of automatic layout of the single line diagram of the annular belt radiation power grid is effectively solved, and automatic layout of the single line diagram can be completed more accurately and quickly by introducing virtual nodes.