Plasmon excitations in two-dimensional binary silicon carbide (SiC) nanostructures are investigated with time-dependent density functional theory. SiC nanostructures have two plasmon resonance bands. Compared with silicene nanostructures and graphene nanostructures, due to change of bond length, two plasmon resonance bands of SiC nanostructures are blue-shifted and red-shifted, respectively. Plasmon resonance excitations of one kind SiC nanostructures depend on edge configuration and nanostructure morphology. However, for another kind of SiC nanostructure, dependence on edge configuration and nanostructure morphology decreases. Plasmon resonance properties of this kind SiC nanostructure are basically the same for impulse excitation polarized in different directions.