The properties of Electrowetting–on–dielectric (EWOD) on the core-surface of optofluidic lens-array with specific “conductive silicon rubber /insulation film” material are one of the important research topics in optofluidics. In this work, the effect of insulation thickness and relative dielectric constant of insulating layer on the contact angle of conductive droplets were analyzed in detail. Then, the characteristics of electrowetting–on–dielectric with different insulating layer materials were also tested. The experimental results show that contact angle increases as the voltage increases. The contact angle varies inversely when changing the thickness of the insulating layer. At a given thickness, it was also observed that the dielectric constant of conductive silicon rubber is of better performance than Parylene. These conclusions are valuable in the field of the design and development of new types of optofluidic zoom lens array devices.