This paper reported a fiber coupled acousto optic device with polarization maintaining ability.The polarization characteristics of acousto optic medium and polarization maintaining fiber were analyzed, and the design and performance parameters of the device were also introduced The experimental device using TeO2 as acousto optic medium，PM980 fiber as coupling fiber. A result of insert loss 2.4 dB, extinction ratio 50 dB and polarization extinction ratio 22.24 dB has been obtained at 1 053 nm operating wavelength and 100 MHz operating frequency.