Two filling schemes based on new sub-aperture shapes are proposed, which can achieve a higher area filling ratio than that for the filling scheme based on a hexagonal close-packed array with traditional circular sub-apertures. By the evaluation of the far-field beam quality and the balance between the energy loss caused by beam truncation and the beam quality improvement by filling factor improvement, an optimal solution is obtained. The simulation results show that these two new schemes can increase the proportion of power in the far field bucket by 9.2% and 13.9% comparing with those based on a hexagonal close-packed array with circular sub-apertures. The proposed aperture filling optimization schemes have some guidance value for increasing the efficiency of tiled-aperture coherent beam combining of fiber laser arrays.