To speed up the conventional method of moments-physical optics (MoM-PO) solution process of antennas mounted on electrically large platforms, a novel method hybridizing the adaptive integral method (AIM) with the PO is presented to solve a coupled electric field integral equation (C-EFIE) resulted from the MoM-PO method. In the hybrid AIM-PO method, both the MoM and PO regions are enclosed in a cube equipping with an auxiliary regular Cartesian grid. Then the standard AIM procedure is employed to efficiently perform matrix-vector multiplications (MVMs) relating to the MoM and PO regions. To accurately model radiation problems, the mutual interactions between the MoM and PO regions can be fully handled with a set of newly proposed translation coefficients and a MVM scheme. The efficiency of the proposed AIM-PO technique is verified through the fast analysis of typical antennas mounted on electrically large conducting platforms.