It is known polyethylene is the most common plastic product and used in a wide range of applications. High density polyethylene (HDPE) with almost no branching has stronger intermolecular forces and is produced mainly in slurry and gas-phase polymerization processes. This work develops a precise steady-state model for the industrial HDPE continuous slurry processes. The characterization of the Ziegler-Natta catalyst existing multiple site types proposed by Khare et al. (2002) is considered in this model. Moreover the PC-SAFT EOS with modified parameters gives good descriptions of the physical and thermodynamic properties and phase equilibrium for the slurry HDPE process. Simulation results demonstrate that this steady-state slurry HDPE model can accurately estimate the major polymer property such as melting index (MI).