By analyzing the aerosol number concentration and the size distribution observed in July 2014 at Mt.Huang, the characteristics of aerosol distribution at Mt.Huang in summer were analyzed.On this basis, log-normal fitting were performed on aerosol size distribution.The results show that the average aerosol number concentration at Mt.Huang is about 3 518.27 cm^-3.The aerosol number concentration is mainly concentrated in Aitken mode.The daily variation of aerosol average concentration showed a bimodal distribution, and the peak concentration was accompanied by the increase of small particles.The aerosol number concentration was negatively correlated with relative humidity and wind speed, and high aerosol number concentration usually occurred under weak southeastern wind condition.The aerosol number concentration in the accumulation mode was obviously influenced by wind direction.With the effect of different air masses, the difference of aerosol number distribution mainly existed in the particle size of less than 100 nm and between 500 and 1 000 nm.Under the southwest air mass with high humidity, there appeared the highest aerosol number concentration and the narrowest size distribution in Aitken mode.However, under the southeast air mass with high temperature and low humidity, there appeared the lowest aerosol number concentration and the widest size distribution.Aerosol number concentration and spectral width corresponding to northern air mass were in medium level.The size distribution characteristics of aerosol ranging from 500 to 1 000 nm were contrary to those in Aitken mode.The aerosol size distribution and volume distribution under different backgrounds can all be fitted to a log-normal distribution by using the three modes of Aitken mode, accumulation mode 1 and accumulation mode 2, but the aerosol number concentration spectral parameters under different air masses were quite different.