Fluidized bed reactor is one of the main units in gas-phase ethylene polymerization processes. Due to the complexity in the polymerization kinetics, hydrodynamic behavior and heat transfer, the modeling and simulation have played an important role in the real operations of industrial polymerization reactors. In this paper, a two-stage modeling strategy for industrial fluidized bed reactors in gas-phase ethylene polymerization processes is proposed. The kinetics of polymerization reactions is computed in the first stage based on a comprehensive kinetics model while the hydrodynamic behavior and heat transfer in the industrial fluidized bed reactors are computed in the second stage based on a set of partial differential equations (PDEs). The polymerization kinetics, hydrodynamic behavior and heat transfer are integrated into the modeling and simulation of industrial fluidized bed reactors in gas-phase ethylene polymerization processes. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.