Abstract: To provide references for atmospheric environmental treatment, we analyzed the multi-time scale variation characteristics of the air diffusion ability and its causes based on the data of atmospheric mix layer height, air diffusion parameters and mean wind speed in Huzhou from 1980 to 2013. The results showed that: (1) it presented a slow increasing trend of the atmospheric mix layer height, the general trends of wind speed and atmospheric diffusion parameter were decreasing, and the wind speed had a significant positive correlation with atmospheric diffusion parameter; (2) the types of monthly variations of the atmospheric mix layer height, wind speed and atmospheric diffusion parameter were all of bimodal pattern; it had a peak in March and August, and trough in July and October, additionally, there were significant positive correlations between these three parameters, and the seasonal variation showed the trend with high in spring and low in autumn; (3) urbanization, heat island effect and dry island effect increased the vertical movement ability of atmosphere, which increased the atmospheric mix layer height. However, the increase of surface roughness decreased the horizontal wind speed, which meant the abatement of atmospheric horizontal motion ability and the atmospheric diffusion ability; (4) moreover, Huzhou was adjacent to Taihu Lake which made its atmospheric diffusion ability similar to that of coastal areas; the thermal difference of land and water, the change of wind speed, mould rains and high temperature had obvious influence on the seasonal variations of the atmospheric mix layer height and the diffusion parameter.