In shear-thinning fluid, there is a special rheological behavior that the apparent viscosity decreases with the increase of shear rate. As the viscosity changes during lateral migration, the lift force acting on particles will also change, so the particle migration and aggregation laws in Newtonian fluids are not completely applicable to shear-thinning fluid. Integrating microfluidic technology, high-speed microscopic image acquisition technology and digital image processing technology, combined with the solved velocity and shear rate equations of shear-thinning power-law fluids, the force analysis of particles is completed, and the influences of particle size, channel flow rate, apparent viscosity and shear-thinning characteristics on particle aggregation are investigated. Results indicate that, in the shear-thinning fluid sodium carboxymethyl cellulose (CMC) aqueous solution, with the increase of channel flow rate, the equilibrium position of inertial lift ΔF=0 gradually approaches the wall surface, and the migration and aggregation location of particles gradually tends to the side of higher shear rate. This leads to the gradual change of the particle distribution from relatively uniform distribution to aggregation at specific locations. As the particle size increases, the aggregation in the shear flow becomes more and more obvious, and gradually closing to the wall. Combining experimental study and theoretical analysis, it is proved that the greater the consistency coefficient K (represent greater apparent viscosity), the more the aggregation position is towards the low shear rate, and the smaller the power law index n (represent stronger shear thinning characteristic), the more concentrated the position is towards the high shear rate. K increases and n decreases with the increase of CMC mass fraction which leads the aggregation position constantly shifting towards the side with lower shear rate. This shows that the consistency coefficient has a greater influence on the migration and aggregation of particles in shear-thinning power-law fluids. It needs to be paid attention to the research of solid-liquid two-phase separation in non-Newtonian fluids in the future.