Technical modeling of x-cut H∶LiNbO_3 optical waveguides is researched by prism coupler at the wavelength of 532 nm and 1310 nm.For optical waveguides proton-exchanged in pure benzoic acid at 150℃,180℃ and 200℃, relationships between exchanged thickness and exchanged time are given, respectively,and on this base,a relation curve of diffussion coefficient of proton-exchange to exchanged temperature is plotted.For the waveguides proton-exchanged at 180℃ and annealed at 350℃,the changes of surface refractive index increment and effective thichness with annealing time are obtained.The results can be used to design and fabricate the low loss α phase single mode waveguides.