Surface plasmons are highly confined electromagnetic modes coherently coupled to collective oscillations of free carriers at metal (or doped semiconductor) interfaces, which can greatly enhance light-matter interaction at the nanoscale and have found valuable applications in areas such as waveguiding, biochemical sensing, ultrafast modulation, detection and nonlinear optics. They are usually excited by diffraction-limited optical approaches with the use of bulky optical components (prisms, gratings,etc), which greatly limit the miniaturization of plasmonic devices and their chip-scale high-density integration. By integrating a plasmonic nanostructure with a quantum tunnel junction, low-energy inelastically tunneled electrons can directly excite plasmonic modes in the nanostructure with advantages such as ultra-small footprint and ultra-fast speed. In this paper, recent research progress in the inelastic tunneling-based electric excitation of localized and propagating surface plasmons is overviewed.