This article introduces the design and application of fiber acousto optic shifter for Doppler laser radar. The operating principle of fiber acousto optic shifter has been described and the design method of the key specifications such as the insertion loss, extinction ratio, frequency accuracy and stability of the device has been focused on. The experimental results of operating wavelength of 1.55 μm, insertion loss of 1.8 dB, extinction ratio of 45 dB and frequency stability of better than frequency×10 -7 have been obtained.