While surface plasmon excitation assisted by nematic liquid crystal layers has been comprehensively studied in different aspects, application of cholesteric structures for surface plasmon excitation remains an unexplored area. Moreover, structures including cholesteric layers and metal grating for surface plasmon excitation have never been considered, to the best of our knowledge. We studied theoretically and experimentally such structures focusing on different regimes of propagation of normal modes in the cholesteric liquid crystal layer. The application of such structures for sensing is accordingly discussed.