To investigate the optical characteristics of haze-fog, sequence diagram of backscattering coefficient, profiles of extinction coefficient, visibility were retrieved from data of laser ceilometer. Combining data from sounding, automatic meteorological station and visibility sensor, analyses of haze-fog process were performed. The results show that the occurrence of haze-fog is strongly influenced by meteorological elements, static, small wind is benefit to the emergence of the haze, while higher relative humidity which has great influence on visibility often leads to coexist of haze and fog. The fog which often occurs in low altitude has stronger backscattering, large vertical rate of change, while haze often has weaker backscattering, smaller vertical rate of change and larger span in vertical direction; The variation of backscattering coefficient in the fog and haze were analyzed, both horizontal visibility and vertical visibility were obtained from data of ceilometer. The horizontal visibility was consistent with visibility from visibility sensor, and the variation of vertical visibility had opposite trends with relative humidity while has the same trends with wind speed. By analyzing variation of backscattering coefficient with time, the Fourier transform power spectral distribution was obtained, this distribution was corresponding with the border characteristics of fog and haze.