Optical Waveguide Array (OWA) was the key parts of Optical Waveguide Array Electro-Optic Scanner (OWAEOS). Propagation and output characteristics of OWA were studied in the finite-difference beam-propagation method (FD-BPM). Effect of structure parameters of OWA on propagation and output characteristics was analyzed. These results showed that core layer thickness,period,length and number of optical waveguide of OWA were of great effect on amplitude and phase distribution on output section and on the full width at half-maximum (FWHM) of main lobe of output beam. By comparing these results with what were obtained in other methods,the FD-BPM was more convenient and comprehensive to describe propagation and output characteristics of OWA. In addition,scanning characteristics of OWA were studied. Then according to the demand of beam scanning,the optimal structure scheme of OWA is presented.