Abstract: To conduct a closed study on cloud condensation nuclei (CCN) at Guangmingding, Huangshan Mountain, physical and chemical properties and CCN number concentration of atmospheric aerosols were observed from June 30 to July 28, 2014.The temporal characteristics of chemical composition, spectral distribution, and CCN number concentration were analyzed.The CCN number concentration calculated by ion-pairing method based on κ-Köhler theory was compared with the observations.The results indicated that the calculated and measured CCN concentrations show close correlation and high accuracy.The results of low supersaturation CCN closure are better than those of the high supersaturation, the CCN number concentration is underestimated when the supersaturation is low and overestimated when that is high, which shows that the chemical composition data of aerosol is very important for the prediction of the CCN number concentration, and the use of this method can lead to the closure of CCN.Considering the influence of 40% Water Soluble Organic Carbon (WSOC) on the hygroscopicity of aerosol particles, CCN closure results are better at the lower supersaturation, but the effect is not significant, especially when the fitting results are relatively low, there is no effect under poor high supersaturation.Therefore, the water-soluble inorganic components in aerosol particles have an important effect on the activation of CCN, while the WSOC, which contains more content, complex chemical components, and uncertain hygroscopicity, has a limited effect on the activation of CCN, which is consistent with some studies that the influence of aerosol hygroscopicity is more important than that of organic components with complex characteristics.