Volatile Halocarbons (VHCs) are important greenhouse gases and ozone-depleting species in the atmosphere. Many observations of VHCs have been previously conducted on land and coastal environment, however, only limited studies focus on the VHCs in the marine boundary layer. In this study, ship-borne measurements over the Northern South China Sea (NSCS) and Northeastern Indian Ocean (NEIO) were conducted from April to June 2019. A total of 16 VHCs were detected in the NSCS and NEIO marine atmospheric boundary layers, with total concentrations ranging from 1.35 to 2.49 ppbv and 1.49 to 2.76 ppbv, respectively. Specially, CH₃Cl, CFC-12, HCFC-22, CFC-11 and CCl₄ were the most abundant species. The distribution and the concentration were different in the two oceans, as well as between open sea and inshore areas. Notably, a higher concentration of VHCs was detected in the open sea, illustrating that may be affected by marine emission and/or long-distance transportation from the land. Four VHCs sources were identified by the Positive Matrix Factorization model (PMF) in NSCS and NEIO, respectively. VHCs in NSCS was mainly caused by refrigerant emissions (41%), biomass combustion (25%), marine organism emissions (20%) and solvent volatilization (14%). For NEIO, refrigerant emissions (47%), marine organism emissions (21%), industrial emissions (19%) and solvent volatilization (13%). Furthermore, backward air-mass trajectory analysis indicated that the air masses of NSCS were mainly originated from the continental area, while the air mass in NEIO was mainly influenced by the continental area, as well as long-distance transportation from the Southern Hemisphere. In NSCS, the concentrations of VHCs of some species showed decreasing concentrations from the offshore area to the open sea, while most VHCs were at higher concentrations in the Bay of Bengal in NEIO. Overall, the anthropogenic emissions of VHCs were higher than those from the natural sources in the marine boundary layer of NSCS and NEIO, which indicated that ocean areas far away from continents were significantly affected by anthropogenic VHCs emissions. Although the implementation of the Montreal Protocol has effectively reduced most of the VHCs emissions, some banned VHCs concentrations remained significant in the marine atmosphere. Therefore, more future attention is needed to further reduce the levels of VHCs in the atmosphere.