On the basis of Surface Plasmon Polariton(SPP) waveguide dispersion relation being derived systemically, the applications of SPP waveguide are summarized in this paper. The slow wave effect in SPP waveguide, the EIT(electromagnetically induced transparency)-like phenomenon, the tunable SPP waveguide filter at optical and microwave frequencies, the SPP waves cloaking through diffraction are mainly introduced. Problems and challenges in this field are pointed out finally, and the future developing trend is prospected. Analysis indicates that reducing the loss of the surface plasmon waveguide materials and the difficulty of the production process by introducing gain mediums and superconducting materials are the problem to be solved urgently in the future.