Due to the large amount of reactive power consumed by conventional DC receiving-ends and the reactive power and voltage is highly relative, the voltage stability problem at the receiving end of DC infeed power grid is serious. At present, there are a large amount of research on a single DC fault, but the research on the interaction among multiple DC faults is insufficient. This article uses the network equivalence method to derive the relationship between bus voltage and voltage of fault DCs after DCs fault simultaneously, summarizes the conditions under which multiple DC faults significantly increase the risk of stability. Meanwhile the selection principles of DC infeed mode at the receiving end based on DC voltage stability characteristics is studied. A method is proposed to determine the areas that require special attention to the simultaneous fault effects of multiple DCs. The proposed method could provide reference for optimizing the structure of the receiving end of DC infeed power grid and improving the reliability of power grid operation.