<p>In this study, a cruise campaign was conducted over China marginal seas to measure concentrations of condensation nuclei (N<sub>cn</sub>), cloud condensation nuclei (N<sub>ccn</sub>) and other pollutants during DOY 110 to DOY 135 of 2018. With exhaustedly excluded self-ship emission signals, the mean values of N<sub>ccn</sub> during the cruise campaign slightly increased from 3.2 ± 1.1 × 10<sup>3</sup> cm<sup>−3</sup> (mean ± standard) at supersaturation (SS) of 0.2 % to 3.9 ± 1.4 × 10<sup>3</sup> cm<sup>−3</sup> at SS of 1.0 %, and the mean value for N<sub>cn</sub> was 8.1 ± 4.4 × 10<sup>3</sup> cm<sup>−3</sup>. Data analysis showed that marine traffic emissions apparently yielded a large contribution to the increase of N<sub>cn</sub> in daytime, especially in marine atmospheres over their heavily travelled sea zones; however, the fresh sources had no clear contribution to the increase of N<sub>ccn</sub>. This finding was supported by the quantitative relations between N<sub>cn</sub> and N<sub>ccn</sub> at SS = 0.2–1.0 % against mixing ratios of SO<sub>2</sub> in self-ship emission plumes, i.e., 1 ppb increase in SO<sub>2</sub> corresponds to 1.4 × 10<sup>4</sup> cm<sup>−3</sup> increase in N<sub>cn</sub>, but only 30–170 cm<sup>−3</sup> increase in N<sub>ccn</sub> possibly because of abundant organics in the aerosols. The smooth growth of marine traffic derived particles can be observed, reflecting aerosol aging. The estimated hygroscopicity parameter (<i>κ</i>) values were generally as high as 0.46–0.55 under the dominant onshore winds, suggesting inorganic ammonium aerosols likely acting as the major contributor to N<sub>ccn</sub> through aerosol aging processes largely decomposed organics. Moreover, the influences of the transported new particles from the continent on N<sub>cn</sub> and N<sub>ccn</sub> in the marine atmosphere were also investigated.</p>