We report on a single-frequency polarization maintaining (PM) ytterbium-doped fiber (YDF) amplifier by using a single-frequency Nd:罽VO4 oscillator seed source and a large-mode-area panda polarization maintaining fiber. The system generates single-frequency radiation up to 17.3 W at 1064 nm wavelength with 62.8% slope efficiency,57.6% optical-optical power conversion efficiency and the polarization extinction ratio is better than 24.3 dB. The spectral characteristic,output power characteristic and polarization characteristic of the single-frequency PM YDF amplifier are discussed in detail.