A coherent beam combining model with 2×2 segment mirrors is developed with a 3D adjustment including 2D rotation and 1D translations to realize phase lock between individual beams for the higher output power. The combining model is simulated using ray tracing and diffraction method, and the accuracy of adjusting parameters with rotations of ±0.5 μrad and translation of ±105.3 nm are obtained. Considering the adjusting tolerance, the system performance is estimated by Monte-Carlo error analysis for flat wavefront and non-flat wavefront. The power ratio within 20 μm diameter spot in symmetrical layout is statistically analyzed compared with that in asymmetrical layout. The results show that the symmetrical layout is effectively beneficial to raise output power level of large-scale high-power solid-state laser by coherent combining.