Optical power of a 397.5 nm ultra-violet laser can be inhabited by the feedback loop based on acousto-optic frequency shifter. The laser power is stabilized through changing the radio frequency power of the frequency shifter by error signal obtained by feedback, and controlling the laser power by the Bragg diffraction of the frequency shifter. The characteristics of the ultraviolet laser generated through frequency doubling is analyzed. Finally, in the time domain, the fluctuation of ultra-violet laser is remarkably decreased from ±11.739% to ±0.053% by the feedback (220 times improvement). In the frequency domain of 1 Hz to 8000 Hz, the power spectra density of laser is dramatically reduced. Typically at 5 kHz, the power spectra density is improved from 9.6×10-5 dBV·Hz-1/2 to 1.9×10-6 dBV·Hz-1/2.