A sensing chip structure of an optical scale reader includes a substrate having at least one conductive pad. The substrate has thereon a photosensitive chip. The photosensitive chip has at least one pin. The pins are each connected to a conductive pad by a conducting wire. A coded graphic layer is disposed on a side of the photosensitive chip, and the side of the photosensitive chip faces away from the substrate. The sensing chip structure is conducive to structural simplification and miniaturization of the optical scale reader.