A novel variable fiber optical attenuator (VFOA)using an electrowetting microprisms (EMPs) and and two self-focusing lenses is proposed . EMPs can change the wetting angle of solid-liquid interface technology by electronic control methods. The attenuation of the VFOA is analyzed by the theory and experimental measurements . Theoretical analysis and experimental results show that a good control effect of light attenuation in the small voltage range (such as 135—139 V),and the optical attenuation range can achieve in 2—60dB. With the merits of novel conception, easy production, low cost and simple structure, the device will be widely used in communications fields after the optimized design. Disadvantage of this device is high voltage, in order to reduce the operating voltage to achieve the purpose of actual use, screening of high dielectric constant material as the dielectric layer material is topic of future research.