We reported on the annealing features of the RbTiOPO4 planar waveguides fabricated by 6.0 MeV C3+ ion implantation. The thermal stability of the ion-implanted RbTiOPO4 waveguide was investigated by annealing at different temperatures ranging from 260 degrees C to 650 degrees C. Results revealed that when temperatures are higher than 550 degrees C, annealing caused the refractive indices of both ny and nz a saturation behavior. An increase of the ny refractive index in waveguide region was observed after proper annealing. The low loss planar mono-mode waveguides have been achieved in RbTiOPO4 crystals by applying appropriate ion implantation and annealing conditions.