Metasurface silicon-based optical devices are highly integrated and high-performance, meeting the requirements of photonics integrated circuits. We present a design method for metasurface silicon-based gradient index (GRIN) optical lens. With easy calculation, this method supports large-area GRIN elements design. The Luneburg lens and integrated coupler are shown as examples. Such devices show good performances in simulations. The simulations show that the Luneburg lens can focus light from all directions equally well. The optical 1-dB bandwidth of the integrated coupler is about 100 nm. Our method provides a convenient and feasible approach for designing silicon-based GRIN lenses.