Localized surface plasmon resonance (LSPR) supported by metal nanoparticles or connected nanostructures was demonstrated as a powerful scheme to enhance the upconversion luminescence signals of upconversion nanoparticles (UCNPs). Three modulation mechanisms of LSPR and four types of UCNP/metallic nanostructures were introduced. The UCNP/metallic nanostructures which remarkably enhance upconversion luminescence are: Rare-earth-doped substrate doped by Ag and Au nanoparticles, core/shell structure, gap structure formed of small distance between rare-earth-doped NaYF4 and metal nanowires, periodic structure of metal arrays. At last, recent advances were reviewed in applications of these UCNP/metallic structures in biomedical and optoelectronic devices.