Abstract: A new acousto-optic modulator based on rare earth ions RE³⁺-doped lead tungstate singlecrystal is presented. The AO figure of merit of PbWO₄ was estimated based on the experimental results of acoustic velocity measurement. It is found that its AO figure of merit M₂ is very close to that of PbMO₄. Furthermore, RE³⁺: PbWO₄ has much wider transmission range in the near UV spectral region with cut-off wavelength at about 330nm. Besides, it also exhibits enhanced resistance to UV-irradiation damage.The central frequency of the modulator is 80 MHz with 20 MHz bandwidth and the diffraction efficiency for 1st order light beam is 85%with 1 W driving power （He-Cd laser in 442 nm）.