Nowadays although the In–N co-doping effects on the optical band gap and absorption spectrum of ZnO are studied extensively, all of the In–N co-doped ZnO materials are of random doping, and the preferred orientation doping using the unpolarized structure of ZnO has not been considered so far. Therefore, in this paper, based on the density functional theory using first principles plane-wave ultrasoft pseudopotential (GGA+U) method, the densities of states and absorption spectra of un-doped and the In–N heavily co-doped Zn1-xInxO1-yNy (x= 0.0625-0.03125, y=0.0625-0.125) in different orientations are calculated. The results show that in the same doping mode, the larger the volume of doping system, the higher the total energy and the formation energy are and the narrower the optical band gap is; the red shifting of absorption spectrum becomes more significant with the increase of In–2N co-doping amount. Those are in good agreement with the experimental results. Under the condition of different doping manners and the same In–2N co-doped concentration, the co-coped In–N atoms along the c-axis orientation, have the narrower optical band gap and more significant red shifting of absorption spectrum than the In–N atoms with the orientation perpendicular to the c-axis. We believe that these results may be helpful for designing and preparing the new photocatalyst materials of In–N heavily co-doped ZnO.