The hydrodynamic characteristics and heterogeneous structures in an airlift loop reactor (ALR) are analyzed by a computational fluid dynamics (CFD) approach. Based on the two-fluid model, a modified cluster structure-dependent (CSD) drag model under consideration of the cluster effects is applied to the prediction of the non-uniform flow structure in the ALR. In comparison with experimental data and the traditional drag model, the present model enables a better prediction. The distributions of the local granular temperature in different regions of the ALR are indicated. The granular temperature in the particle diffluence region was found to be higher than that in the draft tube and annular zones.