Multimode glass planar waveguides were fabricated by K-Na ion exchange technique. The effective indices were measured by prism coupling technique. The refractive index profiles of the planar waveguides were reconstructed by Inverse Wentzel-Kramers-Brillouin method and the best fitted refractive index profile is Gaussian distribution. The fabrication condition of single mode waveguide was got from the dispersion curves and a single mode waveguide were fabricated. The surface refractive index obtained by WKB dispersion equation. The image of propagation in the waveguide was taken by digital camera, from which the light intensity attenuation curves were fitted and the propagation losses were calculated and the propagation loss of the single-mode waveguide is about 0.4 dB/cm.