Dielectrophoresis based Microfluidic system is recognized as being one of the most feasible applications in the field of life-saving procedures such as blood cell differential analysis and cancer cell separation. We present a model for analyzing the trajectory of micro particle by dielectrophoretic field-flow fractionation in microfluidic device and show preliminary results of parametric study. The upper and bottom wall of microfluidic device chamber supports an array of finite microelectrodes; each upper electrode and electrode gap aligns with lower wall electrode gap and electrode, respectively. By enabling apt AC voltage to these electrodes, dielectrophoresis forces are created to levitate micro objects that suspended in the channel of the microfluidic device and the equilibrium levitation heights of the micro objects are affected in proportion to the associated forces and dielectric properties. The model accounts for the external forces associated with inertia, gravity, buoyancy, virtual mass, drag, and dielectrophoresis that acting on the micro-scale particle. The model also signifies the dependency of the path of micro particle on the alternation of voltage, volumetric flowrate, radius of particle, electrode and gap dimensions, and micro channel height. The validity of the model is demonstrated with the representative microfluidic device using water as the medium and polystyrene particle as the micro-scale entity. The findings of the study indicate that the levitation height is independent of micro-scale entity's size and dependent on the applied electric potential and microchannel height.