We have proposed a new method to achieve gradient refractive-index (GRIN)optics via a compoundliquid medium. By adjusting the composition of the liquid medium, the refractive index of the compoundliquid was tuned in a very broad range from 1.58 to 5.15. The liquid medium also exhibited weak frequency dependence. Based on these properties, we designed a liquidGRIN planar lens and experimentally demonstrated the feasibility of this approach. The beam deflection of the lens was controlled by adjusting the distribution of the refractive-index of the lens. By changing the composition of the compoundliquids in different cells of the lens framework, different spatial gradually varied refractive index profiles have been achieved. The proposed liquid planar lens has shown a good directive property at different receiving angles and demonstrated a broadband performance between 12 GHz and 15 GHz. This method results in a rapid and flexible realization of gradient refractive index structures by using liquid medium.