Abstract: This paper investigated the stability of a DC microgrid affected by dynamic interactions among integrated components. The investigation was based on an interconnected model of microgrid with two subsystems. One subsystem was constituted by the examined dynamic component (EDC), and the other subsystem consisted of remainder of DC microgrid (ROM). Analysis was carried out in this paper to examine how the degree of interactions affected by modal condition of two subsystems. It was found when one open-loop oscillation of the examined component was in the proximity of a mode of the ROM subsystem on the complex plane, dynamic interaction turn strong, corresponding closed-loop oscillation moded of DC microgrid might move towards opposite directions as influenced by the coupled components, leading to growing oscillation instability case. Hence this investigation revealed the mechanism about why dynamic interactions inside the DC microgrid might cause instability from perspective of modal condition, and how interaction intensity was affected by the dynamic characteristics of subsystems. An examination method is proposed to detect stability danger by using modal information of subsystems. Finally, study cases of example DC mcirogrids with line regulating converters (LRCs) and converter-interfaced dynamic loads (CDLs) are presented to demonstrate the analysis made above.