Abstract: Micro-nano SiC/epoxy (EP) composites with different filler proportions were prepared with micro and nano SiC as the fillers. The glass transition temperature, room-temperature dielectric spectrum and direct current (DC) conduction of the micro-nano SiC/EP composites were measured. The effects of the interface between filler and matrix on the glass transition temperature, dielectric spectrum and DC conduction characteristics were analyzed. The results show that when the micro and nano SiC fillers are used together, the glass transition temperature of micro-nano SiC/EP composites decreases first and then increases with the increasing nano SiC filler content. At the same frequency, the micro-nano SiC/EP composites have lower relative permittivity and low-frequency loss peak. Compared with EP, the micro-nano SiC/EP composites present significant nonlinear conduction characteristics. In contrast with micro SiC/EP composite, the micro-nano SiC/EP composites have higher nonlinear exponent and switching electric field. The nonlinear conduction characteristics of micro-nano SiC/EP composites are closely related to the interfacial region between SiC particles and EP matrix.