Based on the latest satellite-derived sea ice concentration (SIC) data, this study investigates the seasonal and spatial characteristics of Antarctic sea ice trends from 1979 to 2014, and examines the relative contributions of the Interdecadal Pacific Oscillation (IPO) and Atlantic Multidecadal Oscillation (AMO) phase shift to the Antarctic sea ice trend and associated mechanisms. Results indicate that SIC in the Ross Sea and the Indian Ocean showed increasing trends in the four seasons, and the annual and seasonal Antarctic sea ice extent (SIE) exhibited significant increase trends from 1979 to 2014. During the warm seasons (December-May), SIC decreased significantly in the Amundsen-Bellingshausen Seas and decreased in the Weddell Sea ice, resembling a positive phase of Antarctic Dipole (ADP). During the cold seasons (June-November), the SIC trends in Amundsen-Bellingshausen-Weddell Seas showed a negative phase of ADP. The shift of IPO from a positive to negative phase during 1979-2014 deepened the Amundsen Sea Low (ASL) by exciting Pacific-South America (PSA) atmospheric teleconnection and significantly contributed to the negative phase of ADP in the austral winter and spring. During the austral spring, the shift of AMO from a negative to positive phase during 1979-2014 enhanced the ASL through the excitation of the Rossby wave and PSA wave train across the South Pacific basin and weakened the Ekman suction that would advert less warm water upward, contributing to the negative ADP and increased sea ice trend in the eastern Ross Sea, Amundsen Sea and Indian Ocean and explaining about 75% of the austral spring Antarctic SIE increased trend. In the austral summer, the above IPO and AMO phase transitions might have enhanced the Southern Annular Mode (SAM) and thus contributed to the increased trend of Antarctic sea ice. Our results suggest the seasonality and regionality of impacts of the IPO and AMO phase shifts on Antarctic sea ice trends through the atmospheric teleconnection mechanisms.