The epitaxial semiconductor–metal interface has unique optical properties. However, people know little about the coupling modes at the semiconductor–metal interface of heteronanocrystals both experimentally and theoretically. The coupling between the semiconductor excitons and the metal surface plasmons in the ZnO twin nanorod–Ag heteronanocrystals is studied. These heteronanocrystals are synthesized through photoreduction of silver ions on the ZnO twin‐nanorods. The interfacial epitaxial relation of the perfect heteronanocrystals is found to be (0001)ZnO//(111)Ag. The hybrid exciton energy splitting of 97 meV is observed from the absorption spectrum. The photoluminescence of the hybrid excitons shifts to red significantly relative to that of the uncoupled excitons. The theoretical model concerning the exciton–surface plasmon coupling is proposed to account for the experimental phenomena.