Abstract: In the tiled-aperture coherent beam combining, the low filling factor will reduce the beam combining efficiency. To solve this problem, we proposed a filled-aperture coherent beam combining scheme based on the semi-transparent mirror. We studied the influences of the light intensity difference and wave-front phase error on the efficiency of the beam combination. The results show that it is not difficult to meet the tolerance requirement of light intensity difference and the wave-front phase error requirement in the filled-aperture coherent beam combining. When considering the single factor, if the single beam's intensity is three times larger than the others', the efficiency of the combining can reach 90%. And if the phase error is less than /5, the efficiency of the combining can reach 90.5%. We designed an experimental instrument to verify the feasibility of the filled-aperture coherent beam combining scheme. Experimental results show that, in the phase locked loop system, the output light intensity is very stable, and the efficiency of the combining can be more than 95%.