According to the size distribution parameter and extinction coefficient of soot aerosol, the influence of the number concentration of soot aerosol particles and transmission distance on the link attenuation is analyzed. Combined with the amplitude damping channel, the channel capacity, channel fidelity, and channel bit error rate are numerically simulated. The simulation results show that the number concentration of soot aerosol particles increases from 2.1×10⁶ m^-3 to 3.2×10⁶ m^-3, the link attenuation factor increases from 0.30 dB to 0.46 dB, and the bit error rate increases from 0.008 7 to 0.012 2 at a transmission distance of 3 km. It can be seen that the soot aerosol has influence on the performance of satellite-ground quantum communication, and the degree of influence is different. The simulation results can provide reference for quantum signal transmission under the influence of soot aerosol.