A method of manufacturing an optical waveguide using a laser direct writing method is disclosed. More particularly, a method for improving refractive index profile of the optical waveguide by overlapping two or more beams using Gaussian laser beam is provided. In addition, it can accomplish an improved waveguide characteristics such as an offset structure of an S-bend type optical waveguide and an asymmetrical curve optical waveguide by individually adjusting the overlapped laser beams.