Abstract We proposed an ultra compact polarization beam splitter (PBS) with a short coupling length of 2.82μm consisting of a horizontally slotted waveguide (HSWG) and a hybrid plasmonic waveguide (HPWG). Only the TM-polarized mode can be supported in the HPWG, and the effective index, corresponding to the TM-polarized mode, in the HPWG is similar to that in the HSWG within a wide wavelength range. Consequently, the TM-polarized mode in the HSWG could be coupled into that in the HPWG. As a result, the TE- and TM-polarized modes are split. Such a PBS exhibits a high extinction ratio of up to −20dB within an ultra wide wavelength range of 130nm. Moreover, fabrication tolerances of the PBS are investigated.