The invention provides a dynamic power network topology modeling method and system. The dynamic power network topology modeling method comprises obtaining device information of power network devices,configuring device main bodies of the power network devices to be top points, and configuring internal and external connection terminals of the power network devices to be terminal top points, configuring attribute information for each top point and each terminal top point according to the device information; configuring connecting edges according to ownership relationships and connection relationships among the top points and the terminal top points; and connecting the top points and the terminal top points through the connecting edges, and generating a network topology model of the power network devices. By employing the designed dynamic power network topology modeling method, modeling of a large-scale dynamic power network is achieved, the large-scale dynamic power network topology modeling speed is greatly increased, a data basis is provided for subsequent topology analysis, and therefore the topology analysis performance is improved.