The invention relates to an electric control focal variable fluid lens, based on the medium electric wetting, belonging to the optical focal variable lens. The invention comprises a hollow chamber that containing one conductive or insulated or part insulated ring and two fluids while it is clamped between the transparent basic plate and the transparent cover plate; the transparent basic plate is coated by the conductive film and hydrophobic insulated medium film with special patterns; the bottom of ring has hydrophilous nature, while the top and inner and outer walls have hydrophobic property; the bus of inner wall of ring is a straight line or curve which can be bended in any angle; the ring is parallel with the basic plate and the cover plate with some distance between them. The invention can make conductive or polar fluid in the center by themselves, with simple structure, lower cost, non mechanical movable elements, large focal variable range, high speed, clear image, and lower power consumption. It can be used in photo telephone, endoscope, etc.