Extinction spectra of Ag nanorod arrays under incident light with different polarization directions are calculated by an electrostatics approximation theory. A longitudinal resonance mode of the localized surface plasmons (LSPs) can be excited when the polarization direction is parallel to the long axis of the nanorods, while a transversal resonance mode of the LSPs can be excited when the polarization direction is perpendicular to the long axis. In this case, high-performance plasmonic micropolarizers based on the different resonance wavelengths of the two modes can be designed by use of the Ag nanorod arrays. The polarization property of the Ag nanorod arrays at the longitudinal resonance wavelengths is prominently better than that at the transversal resonance wavelengths, and the resonance peak of the longitudinal mode can be tuned in a broad spectra region by adjusting the aspect ratio of the nanorods. The wavelength of the micropolarizers can be tuned from the visible to near-infrared spectra region by changing the aspect ratio of the nanorods. Moreover, the extinction ratio and insertion loss can also be adjusted by control of the diameter and length of the nanorods.