Carbon neutrality is a global banner for tackling climate change. China，as the largest developing country with huge CO₂ emissions，faces huge challenges in achieving the goal. Currently，there are two pathways proposed. One is to reduce anthropogenic emissions of CO₂ to the atmosphere，and the other is to increase negative emissions of CO₂ from the atmosphere. The ocean is the largest active carbon reservoir on the Earth，with carbon storage capacity of ten times that of the land and fifty times that of the atmosphere，and thus has a great potential for negative emission. China has vast coastal areas with diverse environmental conditions for various negative emission approaches. Current progresses in the studies of marine carbon sequestration theories have laid a solid base for ocean-based negative emission engineering. Through the combination of experimental simulations and field practices，a variety of feasible negative emission approaches will be developed，and a series of quantifiable，repeatable and verifiable protocols will be established，which can not only provide scientific and technological supports for China to achieve the strategic goal of carbon neutrality，but also contribute “China solutions” to cope with global climate changes.