A novel variable optical attenuator device of based of variablefocus liquid lens was proposed and fabricated, of which basic structure included a cylindrical precisiontube as the lens chamber and its side wall sandwiched between two collimators. Liquid lens approximated as optical wedge to form structure of “input collimator＋adjustable lens prism＋output collimator”, the optical axis of the collimator run through the edge of the variable lens. The light emitted by the input fiber collimator deviated from the output fiber collimator best receiver position, through liquid lens electrowetting on dielectric analoging prism, to realize the fiber collimators coupling lightintensity and control optical attenuation. The experimental results show that the range of attenuation values of variable optical attenuato rise up to 2~53 dB, and can be used for demonstration of optical communication experiment, experimental teaching or other occasions.