The effect of the initial phase distortion of the laser on near-field transmission characteristics in free space is investigated both numerically and theoretically. It is demonstrated and proposed that the near-field modulation and fluence contrast of the output laser beam are changing with the increase of both spatial low- and high-frequency wavefront distortion. The simulation results show that in order to ensure the beam quality in propagation, the Fresnel number should be controlled not <50 generally and the wavefront distortion should also be minimized by controlling both low- and high-frequency phase coefficient not larger than 0.6.