Detailed micromechanical analysis of an individual bubble injected into a three-dimensional incipiently fluidized bed is carried out by means of a coupled CFD-DEM approach. The distribution of interphase drag force vectors is consistent with the gas flow pattern based on the potential flow theory. The non-uniformity of drag force caused by bubbles is quantitatively analyzed. Moreover, a bubble-induced inhomogeneous coefficient is presented to assess the ensemble bubble impact. The effects of particle diameter and gas injection velocity are evaluated. The results reveal that the bubble negative effect on interphase drag force is strengthened by increasing the particle diameter and gas injection velocity. (C) 2020 Elsevier B.V. All rights reserved.