By adopting proper temperature field, growth parameters and pulling-annealing technique a series of high quality ZnO doped lithium niobate (LN) crystals were grown by Czochralski method from the congruent melt. The defect structure of Zn: LN crystals was studied by X-ray analyses, IR and Raman spectrum. It is suggested that Zn ions first occupied Nb ions on Li sites, then Zn ions occupied the ordinary Li sites. Its photo-refraction threshold indicated crystal containing 6 mol% Zn: LN has the highest resistance to optical damage, similar to Mg doped LN (5 mol% MgO), having increased two orders of magnitude.