The invention provides a method for analyzing DC power flow in a dynamictopology electric grid, belonging to the electric grid safety technical field. The method is characterized in that the method sets up an incidence matrix and a transmission line admittance matrix; according to net injection powers of electric grid nodes, the generalized inverse solution power flow equation is used. The methodcan be applied to connected or disconnected electric grids, and the analysis for the topological connectivity of the electric grid is unnecessary, and the selection of reference nodes in the electricgrid is also unnecessary, thereby the method brings great convenience for analyzing DC power flow in the dynamictopology electric grid.