Time-dependences of the beam intensity profile along the m lines of different waveguides which prepared by use of various methods were measured. The result demonstrated that the waveguides by ion migration had higher resistance ability of optical damage. These waveguides were prepared by use of the salt bath method in AgNO3 by applying electrical field proposed by Y. X. Chen et al. and the C6H5COOH melt bath method of Bell Lab. When optical damage arises, the anglular width of propagating beam in this waveguide which produced by in-plane scattering could reach to 40°. In rogard to the relation between th? method of formation of the waveguide and its resistance ability of optical damage, author proposes that when one method makes oxidized state of impurities ions tend to more stable, in other words, increasing Fe+++/Fe++ (or Cu++/Cu+，Mn++)ratio, the resistance ability of optical damage of the waveguide prepared "by such method is higher. Otherwise when waveguides are easy contaminated by impurities in preparation process, the resistano? ability of optical damage is lowor. In addition at high operation temporature (specially close Ourie point) the transformation could take place, thus the resistance ability of optical damage is lower.