The process of converting solar energy into useful forms of energy (electricity; chemical energy) is a matter of great research interest today. In which, the use of plasmonic resonance effect of nanoparticles (Au;Ag) in plasmonic nanocompsosite materials is promised to improve the efficiency of the above energy conversion processes. In this report, we present some research results in our group on fabrications of nanostructure materials based on several transition metal oxides and incorporations of Au nanoparticles to investigate the influence of the plasmonic resonance effect on the energy conversion of these materials systems. Different morphologies of TiO₂, ZnO, and MoS₂ nanostructures including nanoparticles, nanowires, nanorods, and nanosheets have been successfully fabricated by both chemical and physical methods. Au nanoparticles were dispersed into these materials by chemical method or evaporation method in combination with thermal annealing. The research results show that the use of Au@TiO₂ nanocomposite material as the electron conductive electrode in solar cells has significantly increased the efficiency of this plasmonic solar cell component. Similarly, the plasmonic effect of Au nanoparticles also significantly increased the photocatalytic activities of Au@ZnO and Au@MoS₂plasmonic nanocomposite materials. Moreover, the studies also showed the effects of the size and density of Au nanoparticles on the energy conversion process in the materials systems.