Abstract: Embodiments of the present disclosure provide a silicon-based optical antenna with a reflective layer and a preparation method therefor. The silicon-based optical antenna comprises: an SOI substrate, the SOI substrate at least comprises a bottom silicon layer, a buried oxide layer, and a top silicon layer, the buried oxide layer is located between the bottom silicon layer and the top silicon layer, the top silicon layer is etched to form a row of waveguides, spacings between the waveguides in the row of the waveguides are in an uneven distribution, each waveguide of the row of the waveguides is etched with gratings, the bottom silicon layer is formed with a groove directly reaching a surface of the buried oxide layer facing the bottom silicon layer, and the surface of the buried oxide layer in the groove is formed with a metal reflective layer.