A waveguide-type visible and near-infrared photodetector structure and preparation method thereof are provided. The structure includes a dielectric layer, a cladding layer, an optical waveguide layer, an intermediate layer, and an electroabsorption layer from top to bottom; the electroabsorption layer and the dielectric layer are communicated through an optical-layer-to-electronic-layer via structure; the dielectric layer is made of a single-crystal or polycrystalline semiconductor material. The method enables the fabrication of a waveguide-type visible and near-infrared photodetector with large bandwidth and high sensitivity, and has the advantages of fewer process steps and a simple driving circuit design.