A compact silicon-based polarization splitter (PS) is proposed using a three-guide directional coupler composed of a silicon nanowire in the center and two horizontal/vertical hybrid-plasmonic waveguides (HPWs) at outer sides. Utilizing the evanescent coupling, the injected TE/TM modes in the central silicon nanowire can be only coupled to the horizontal/vertical HPWs, leading to the separation of input polarizations. Moreover, to improve the extinction ratio (ER), an S-bend connecting with the vertical HPW is employed. Results show that a coupling length of 6.5 (4.5) $\mu \text{m}$ is achieved at the wavelength of $1.55~\mu \text{m}$ with ER and insertion loss of $\sim 18.9$ (15.2) dB and $\sim 0.44$ (0.89) dB for TE (TM) mode, and the bandwidths can cover the entire C-band for both polarizations. In addition, fabrication tolerances to the structural parameters are presented and field evolution through the designed PS is also demonstrated.