Abstract: Irradiance superposition of laser array in far filed is an effective way to achieve output laser beam with high power and high beam quality. However, the wavefront of laser beams will distort in the process of transmission. Because of the distortion of wavefront, in the far-field the irradiance distributions are not smooth anymore. Based on the Huggens-Fresnel principle, the incoherent beams combination model of random phase distorted Gaussian beams with 2D rectangular symmetry array was established. The variation of far-filed focus quality in beams combination was simulated. The relationships between PSD as well as RMS in the far field and the number of combination beams were calculated. The analytical and numerical calculation results were given to illustrate that incoherent combination of Gaussian beams not only can raise the output power, but also improve the quality of output laser.