To account for the sub-grid heterogeneity of gas-solid flow in the multi-phase particle-in-cell (MP-PIC) method, a structure-dependent drag model is proposed in this work by taking into account the particle/parcel position information. The parcel is viewed as a cluster of particles. The local, inter-parcel porosity is calculated by using the method of smoothed particle hydrodynamics (SPH), while the intra-parcel porosity and the diameter of cluster are closed by using the energy-minimization multi-scale (EMMS) model. The local velocities of gas phase and different solid parcels are determined by using the constraint of pressure drop balance between phases as in the EMMS model. The drag force acting on each parcel is then determined with the sub-grid information of velocities and porosities. A bubbling fluidized bed and a circulating fluidized bed riser are simulated to validate this drag model. And the results show good agreements with experimental data. (C) 2018 Elsevier B.V. All rights reserved.