A polarization filter at the two communication windows of 1310 and 1550 nm based on photonic crystal fiber (PCF) with two large-diameter gold-coated air holes is proposed. The effects of geometrical parameters of the PCF on the performances of polarization filter are evaluated by finite element method (FEM). Numerical simulations reveal that the polarization filter possesses ultra-short length of 1 mm and high extinction ratios of 396 and −292 dB at the communication wavelengths of 1310 and 1550 nm, respectively. The bandwidth of extinction ratio (ER) better than 20 dB is 181 nm at the communication window of 1310 nm. Moreover, the bandwidth of ER better than −20 dB is 423 nm at the communication window of 1550 nm.