In the face of the problems of moisture degradation and electrical performance damage caused by repeated condensation of bushings in electrical cabinets in rainy summer, high temperature and high humidity, and morning fog in autumn and winter, 10kV cable butt bushings were selected as samples. The condensation heat transfer rate K of bushing condensation process under different relative humidity, relative temperature difference and fog water conductivity conditions was studied in artificial and natural high humidity environment tests. The droplet morphology characteristics (particle size distribution uniformity index n and fractal dimension Df) of saturated condensation state were extracted based on image processing, and the influence of high humidity environment on the electrical performance of bushing condensation state was obtained. The results show that the K value is greater when there is no electrification condensation than when there is electrification condensation, the distribution range of n is relatively wide under different relative humidity and relative temperature difference conditions, and the distribution range of Df is wider under the influence of fog water conductivity and relative temperature difference. The corona and flashover voltages decrease to varying degrees when the relative humidity increases, the relative temperature difference increases and the fog water conductivity increases. In a high humidity environment, the continued increase in humidity has no obvious effect on the corona inception voltage of the cable casing. When the relative temperature difference and the conductivity of the fog water increase, the corona inception voltage and the flashover voltage decrease significantly.Specifically, when the relative temperature difference is 20 ℃, the corona inception voltage and flashover voltage decrease by 31% and 41% respectively. Compared with the clean fog environment, the corona inception voltage and flashover voltage are reduced by about 50% when the fog water conductivity reaches 2000 μS/cm.