The complex structure and system parameter identification of large thickener are the key causes restricting the understanding of solid-liquid two-phase flow and sand settlement behavior. In this paper, we present a set of operational parameter identification methods for the fuzzy system of a large thickener based on the settling mechanism. The numerical model of 30 m thickener in Chehe beneficiation plant was established, of which the feed velocity, feed particle size distribution and feed volume fraction were identified in turn. A large number of numerical simulations point out that the characteristic structure of the feedwell of the 30 m large thickener in Chehe beneficiation plant makes its natural dilution function better, but the dynamic energy dissipation performance is poor, and there is still much room for improvement in the structure of the feedwell. Also, the sedimentation law of particles of each particle size are given.