Abstract: The present invention belongs to the field of integrated optical waveguide modulation, and specifically, relates to an ultra-close-range metallic heater thermo-optic phase shifter, which includes: a substrate, and a metallic heater and an optical waveguide respectively arranged on the substrate; in which the metallic heater and the optical waveguide are arranged at a close distance, and the distance is less than 600 nm. The material of the metallic heater is titanium, titanium nitride, aluminum, gold, and/or a metal with a larger imaginary part of the refractive index. The present invention includes two solutions: side heating and top surface heating.