Si3N4/SiC interface structure in SiC-nanocrystal-embedded a-Si3N4 nanorods was studied by high-resolution transmission electron microscopy. The SiC-nanocrystal-embedded a-Si3N4 nanorods were synthesized by the method of carbothermal reduction of SiO in pure N2 atmosphere, while the SiC nanocrystals were produced from a substitution of SiC for Si3N4. Between SiC and Si3N4, there are three kinds of plane configurations and a set of orientation relationships, i.e., Si3N4, and nearly (111)SiC//(1010)Si3N4 with low-angle discrepancy of either 3