The paper deals with the numerical simulations on propagation of a focused CO2-laser beam ( l= 10.6mm) in the moist atmospheric hazes of different chemical composition under different meteorological visual ranges. The problems on an optimal variation of the beam radius, focusing angle, and the slope of the front edge of the pulse at the constant pulse energy are investigated in order to determine the requirements for improving the transmission of the propagation channel. It is shown in the paper that the proper variation of the beam's parameters yields a 50 to 70 per cent improvement of the channel's transmission in dry hazes and 10 to 15 per cent in the moist ones because of making the conditions of plasma cells formation poorer. The influence of the atmospheric humidity results in the decrease of the laser spark length by 1.2 to 2 times. The variation of the absorbing particles composition causes the changes in the atmospheric transmission which do not exceed 10 percent.