An electrically tunable pico-projector adopting a liquid crystal (LC) lens as an active optical element is demonstrated. The focal length of this picoprojector is electrically tunable from 350 to 14 cm and the tunable range is even wider than that of a manually focused pico-projector. The response times of turn-on and turn-off are approximately 313 and 880 ms, respectively. In addition, the location of the projection lens can affect the electrically tunable range of the system. A small shift of the projection lens results in the large tunable focusing range of the pico-projector and a tunable focusing range is determined by the LC lens. The optical analysis is also discussed. This concept can even be applied to design other electrically auto focusing pico-projectors based on other optical elements such as liquid lenses and spatial light modulators.