The invention discloses a method for calculating a static voltage stability domain boundary coefficient based on a dynamic equivalent circuit. The method comprises firstly, obtaining a voltage stability weak node by an online load impedance mode margin index; then, obtaining the voltage and current data of all nodes in a current power system by online measurement, obtaining the Thevenin equivalentparameter of the power system, equating the power system with a two-node Thevenin system by using the Thevenin equivalent parameter, and obtaining and arranging the Taylor expansion of an equivalentpotential with respect to a control parameter, so as to obtain the static voltage stability domain corresponding to the current power system weak node according to the necessary and sufficient condition of the critical instability of a single-machine single-load voltage, the equivalent reactance and the equivalent potential in the Thevenin system, and the Taylor expansion; finally, obtaining the boundary coefficient of the static voltage stability domain corresponding to the current power system weak node.