Northern Hemisphere Glaciation (NHG) is one of the major climate change events during the last three million years. From Pliocene to Pleistocene, the Earth gradually cooled down due to ice sheet growth in the Northern Hemisphere high latitude region growth accompanied with atmospheric CO₂ decreasing. However, lack of evidence from high latitude Southern Hemisphere hinders our understanding of the role of Southern Ocean. Here, we present the foraminifera fauna assemblage during 2.8–2.4 Ma and the sediment total organic carbon (TOC) record from 3-2.4 Ma from International Ocean Discovery Program Site U1541 (54°12.756′S, 125°25.540′W, 3604 m). Total planktonic foraminifera mass accumulation rates basically followed the glacial-interglacial cycle. In glacial periods, cold condition may not benefit planktonic foraminifera, so the mass accumulation rates were lower than those in interglacial ones. During 2.8-2.5 Ma, Globoconella spp. was the domain group which suggests that the surface ocean stratification was strong stronger, whereas ~2.5 Ma, Neogloboquadrina pachyderma increased rapidly and became the domain species ever since, indicating that the sea ice growth and/or sea surface temperature decreasing. Over the study period, TOC (%) is higher in glacial than in interglacial, and it had a long-term increase after NHG. Evidence suggests that the Southern Ocean carbon reservoir became larger after NGH dur to the sea ice expansion and following poor ventilation which allow more organic carbon to be preserved in glacial periods. This study provides new insight on the atmospheric CO₂ concentration decreasing due to the ocean-atmosphere dynamic response to the global gradually cooling trend in the Plio-Pleistocene transition.