An electrically tunable-focusing optical zoom system using two composite LC lenses with a large zoom ratio is demonstrated. The optical principle is investigated. To enhance the electrically tunable focusing range of the negative lens power of the LC lens for a large zoom ratio, we adopted two composite LC lenses. Each composite LC lens consists of a sub-LC lens and a planar polymeric lens. The zoom ratio of the optical zooming system reaches ∼7.9:1 and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescope and pico projectors.