A silicon-based silica optical waveguide phased array chip was designed and fabricated. The chip consisted of three parts, including a beam splitting unit, a phase modulation unit and an output waveguide array. The splitting unit was cascaded by three 1×2 optical beam splitters. The phase modulation unit adopted the method of thermo-optic modulation, and the output part comprised 8 dense array waveguides. Light output from 8 waveguides formed interference in the far field, becoming scanning beam. Passing through the thermal photo-effect of the silica after power-on,when the refractive index changed by 0.027%(0.000 4), the scanning beam changed by 5.5°. The waveguide phased array adopted 2.0% ultra-high refractive index difference silicon-based silica waveguide as material, which was fabricated by material growth and annealing by plasma enhanced chemical vapor deposition and then etched by inductive coupled plasma dry etching technology, and finally cut and polished. The test results show that the static output of the eight output array waveguides forms a clear interference spot. When voltage is up to 130 V, the scanning beam angle changes by 5.5 °.