Plastic nanowire-grid polarizers based on small period, 58 and 75 nm half-pitch, Al gratings are fabricated and studied. Al gratings are made by coating Al on the polymer grating sidewalls at oblique angles. The nanopolymer gratings on plastic film over large area are made by nanoimprint lithography. By optimizing the grating period, grating linewidth, Al coating depth, and thickness, excellent maximum transmittance (T-max) (80%-90%) and extinction ratio (similar to 30 dB) are achieved.