In this paper, the hybrid coupling between long-range surface plasmon polariton (LRSPP) waveguide mode and dielectric waveguide mode has been studied theoretically and experimentally in detail by considering its dependence on the structure parameters and wavelength. It is demonstrated that extremely high coupling efficiency (>;99%) has been achieved for TM polarization, while no coupling could happen for TE polarization between these two kinds of waveguides. Based on this hybrid coupler, a polarization splitter with pure TM-mode output from one arm and TE-mode output from the other arm with high TE/TM extinction ratio has been realized. Additionally, this kind of coupling between different waveguides is very significant for providing an effective approach to connect the LRSPP-based devices with the conventional dielectric devices.