LiNbO3:Ru crystals have been grown by Czochralski method, then oxidized in O2 for 20 h. Dependence of recording characteristics of grating on recording wavelength, as well as effect of oxidation treatment on transmission spectra and recording characteristics, has been investigated in LiNbO3:Ru crystal. The results show that the optimal recording wavelength is 458 nm; oxidation treatment increases the absorption of crystals, and also increases the recording sensitivity and saturated diffraction efficiency, which is different from the dependence on oxidation state in LiNbO3:Fe crystals. The abnormal oxidation state dependent characteristics may be induced by that the dark attenuation mechanison of electron tunneling is present, and Ru is in more than two valence states.