Abstract: Volatile halocarbons (volatile halocarbons, VHCs) are important trace greenhouse gases and ozone destroyers in the atmosphere. The concentration, distribution characteristics and sea-to-air flux of trichlorofluoromethane (CFC-11), methyl iodide (CH₃I), dibromomethane (CH₂Br₂), and bromoform (CHBr₃) in the surface seawater and atmosphere of the East China Sea were investigated in October 2022. The results showed that the average concentrations of CFC-11, CH₃I, CH₂Br₂ and CHBr₃ in the surface water were (8.68 ± 6.65) pmol/L, (3.51 ± 1.51) pmol/L, (2.97 ± 1.38) pmol/L and (6.76 ± 3.25) pmol/L, respectively. Affected by various factors such as terrestrial input, biological and photochemistry release, the concentrations of four VHCs in surface seawater were high in the nearshore and low in the open sea. In the S01 section, the vertical distribution of VHCs concentrations had a common feature with the maxima appearing in the bottom layer, which was caused by the release of VHCs from marine sediments to the bottom water. The mean atmospheric mixing ratios of CFC-11, CH₃I, CH₂Br₂ and CHBr₃ were (193.39 ± 69.48) pptv, (0.77 ± 0.63) pptv, (1.49 ± 0.28) pptv and (6.74 ± 2.75) pptv, respectively. Combined with meteorological conditions and backward trajectory analysis, it was found that terrestrial air mass transport, air mass diffusion and sea-to-air exchange were important factors affecting the distribution of VHCs in the atmosphere. The sea-to-air flux data indicated that the East China Sea acted as a source for CFC-11, CH₃I and CH₂Br₂ and a sink for atmospheric CHBr₃ during the study periods.