Planar optical waveguides were fabricated by Cu +-Na + ion-exchange on soda-lime glass substrate. The effective refractive index was measured by prism-coupling technique at the wavelength of 632.8 nm. Refractive index profile was determined by Inverse-WKB method. Results are compared with mathematical solutions, the best fit to the index experiment data is Gauss function. Therefore, the diffused coefficient of Cu +-Na + ion-exchange at 580℃ is De≈2.223×10 -15 m 2/s.