In microfluidic applications, in order to produce the high yield of desired product, the study of particle migration is very important to enhancement and increases the efficiency of positioning and sorting process. One of an effective and robust method for visualization imaging, passively positioning and sorting microparticles and cells without the assistance of sheath fluid is electrical capacitance. In this study, to study the behavior of particle migration, a fine particle concentration in a cross-sectional microchannel is determined for the high dense initial particle concentrations (ξ=10.0%) and small particle diameters (dp= 2.1 μm) by using a high speed multiplexer and 12 multi-layer electrical capacitance tomography (ECT) sensing to discuss the stream migration along five cross-sections. The polystyrene particles as solid phase and non-conductive deionized water as a liquid phase are non-uniformly injected into the inlets microchannel. From the electrical capacitance distribution, the tomography images that show the equilibrium particle migration is reconstructed by used the Tikhonov regularization method. It has been observed that the particle concentration at the wall vicinity area is increased as ξ and dp are increased while the particle concentration at the center area is decreased. It shows the particles are moved away from the center towards wall vicinity area and particles migrated towards the wall increased in the outlet area as the particles move along the cross-sectional microchannel. The experimental result is verified with the COMSOL simulation.