The invention provides a power grid loop detection method. The power grid loop detection method comprises the following steps: acquiring device information and connection information of a power grid device, and establishing a power network topological graph by utilizing the device information and connection information of the power grid device according to a graph theory; and carrying out the loopdetection according to the power network topological graph, counting a total number of power grid loops, and recording a single loop route of each power grid loop. According to the power grid loop detection method designed by the invention, the power network topological graph is established according to the graph theory, and the loop detection function for the power grid device is realized by processing the graph data; and the ordinary topological loop detection of the power grid device is realized by utilizing calculation and union-find set algorithm of a comparison degree, and the multi-power loop detection of the power grid device is realized by utilizing a breadth first search algorithm, so that the detection efficiency of a large-scale power grid network is improved.