The random disturbance of the diffusion parameters σ_y and σ_z isanalyzed with the conclusions: (1) wind speed has a significant impacton the variation of σ_y and σ_z with the leeward distancc and (2) therandom disturbance cannot be neglected in the calculation of the shortterm concentration model. These conclusions have been confirmed bythe diffusion data obtained from the Dachang area of Nanjing for Octo-ber 1983 and wind speed correction has been made for the variation σ_yand σ_z with the leeward distance. The probability of the diffusion pa-rameters obtained from the probability distribution of wind speed canthus be used to describe the probability distribution of the short-termdistribution.