The invention relates to a method and device for quantification of the voltage stability margin of a converter bus in a mode of direct current layered access to a receiving end. The method includes the following steps: according to a load type of load nodes in an electric power system, making the load nodes equivalent to virtual load nodes; determining power grid parameters between direct current layered feed-in points and the virtual load nodes, and utilizing the power grid parameters to build a circuit equation of the direct current layered feed-in points; determining equivalent single-port network parameters of the direct current layered feed-in points according to the circuit equation; and utilizing the equivalent single-port network parameters to determine the voltage stability margin of the direct current layered feed-in points. According to the technical scheme provided by the invention, an alternating current/direct current is equivalent to a single-port network from a direct current drop point, the other direct current drop point and influence of system load on the drop point are reflected by virtual voltage, virtual impedance or virtual power, and after equivalence is completed, the voltage stability margin of the drop point is obtained through an impedance matching theorem.