We report, for the first time to our knowledge, the formation of single mode planar waveguide in z-cut YVO 4 by 400keV, 500keV He ion implantation in fluence of 3×10 16 ions/cm 2 at room temperature or at liquid nitrogen temperature (77K). We investigated annealing behavior of the guiding mode and near-field image in the waveguide by prism-coupling method and end-face coupling method respectively. We found that the effective refractive index of the TE 0 mode was different before and after annealing for the samples implanted at room temperature, while, annealing had nearly no influence on the effective refractive index of the TE 0 mode of the samples implanted at liquid nitrogen temperature (77K). After annealing at 600K for 1h, no guiding mode was observed in the sample implanted by 400keV He ion in fluence of 3×10 16 ions/cm 2 at room temperature. The Rutherford backscattering/channeling technique was used to investigate the damage reduction after annealing treatments. The minimum yield of the implanted, annealed sample was 5.43%. We reconstructed the refractive index profiles in the waveguide under different condition by applying intensity calculation method.