The motion of 3C 120 Jet relative to the core is reasonably uniform and the VLBI scale jet connects outwards to a VLA ~ 100kpc scale. We measured the jet width variation from the center and found some indication of a power law which indicates the jet expands roughly with a constant opening angle and a constant flow velocity, $V_{f}{cong}c$, from subparsec scales to ~ 100 kpc. With such a constant flow velocity and based on other physical parameters deduced from observed emission characteristics of the jet, we have established an equipartition jet model which might accommodate the basic parameters of the jet on subparsec scales, with which one can fit the radio intensities over all the scale of the jet even to ~100 kpc.