Based on the reanalysis of ship-borne continuous data observed in 2012 and 2014 and “bottom-up” and “top-down” approaches, the combustion efficiency and CH₄ emission rate of flaring equipped on oil and gas platforms in the Penglai Region of the Bohai Sea were studied. The results showed that peak atmospheric CO₂ and CH₄ mixing ratios of approximately (11~20)×10^-6 and (100~260)×10^-9 were observed in the downwind area of flaring. The calculated combustion efficiency of associated gas flaring was (97.8±1.1)%, which was better than that in most countries worldwide. The CH₄ emission rates of flaring equipped on the oil and gas platforms were 3.6~6.1 Gg/a and 1.80~2.68 Gg/a, estimated using the “bottom-up” and “top-down” approaches, respectively, indicating that the flaring was the primary source of atmospheric CH₄. On the other hand, the difference in the results estimated by the “bottom-up” and “top-down” approaches was still remarkable, mostly due to the limited spatiotemporal representation of emission factors and observation data. This study is beneficial for promoting the recycling and reuse of associated gas and reducing CH4 emissions from marine oil and gas exploitation in China.