A novel on-chip TM polarizer with high performance is proposed on the 340 nm-thick silicon-on-insulator platform. The polarizer is mainly based on the designed subwavelength gratings, in which the fundamental TM mode acts as guided mode, while the fundamental TE mode acts as leaky mode. Simulations indicate that the polarizer with the SU8 cladding exhibits a broad bandwidth covering all optical communication bands with low insertion loss (IL < 0.5 dB), high polarization extinction ratio (PER > 25 dB), and compact footprint (16.9 x 10.5 mu m(2)). The TM polarizer exhibits strong robustness to wafer thickness and fabrication error. Due to its unique working principle, our proposed polarizer can be compatible with different materials of the upper cladding. By optimizing the parameters, the polarizer can achieve outstanding performance with other upper cladding, such as silica.