An electro-conjugate fluid (ECF) is a kind of dielectric fluid which produces a powerful flow (ECF jet) when subjected to high DC voltage. The ECF jet is a promising micro fluid power source for actuators and sensors including micro motors  , liquid rate gyroscope   etc. However, these applications are developed upon trials and errors because the theory of the ECF flow has yet to be fully established. In this study we introduce the Coulomb force to develop an ECF flow model. Then we hypothesize that the Coulomb force is occurred by two causes; an inherent dominant charge depending on each fluid and a charge injected from a sharp electrode. The hypotheses are proved by the experimental results in this study.