Atmospheric extinction of the He-Ne laser has been measured in Hefei district. The results show that the extinction coefficients are strongly correlated with the concentration of aerosol particles with the radius of over 0.25 ×m. The value of linear correlation coefficient has been found to be 0.91. Howerer, as opposed to the results of ref. [1], the atmospheric extinction coefficient data seem to indicate that no obvious correlation exists with relative humidity of up to 75%. Therefore, we think that the aerosol present in Hefei during the measuring period is strongly inhygroscopio.