In order to understand the sea ice types and its region of origin frozen in Weddell Sea, 27 ice cores were taken from Weddell Sea, Antarctica during September and October, 2006. Their crystals were analyzed, and their ice forming processes were evaluated based on the crystals. Photos of the thin sections from two whole ice cores, and from polygonal granular superimposed ice were taken as well as corresponding stratigraphy descriptions. Vertical profiles of salinity, density and grain size were also obtained. Based on ice core structural texture, the findings include that: 1) although large and smooth ice floes were selected as the investigation sites, the ice sheet at the sampling position may be formed by rafted ice, consolidated ice ridges and second-year ice which were affected by dynamic and thermodynamic processes together subsequently. Ice formed in pure thermal growth comprises minority. The polygonal granular superimposed ice from refrozen wetted dense snow is one type of the ice in Antarctica. 2) Of the all 27 ice cores, the granular, mixed granular-columnar and columnar crystals in sea ice occupy 28.7%, 14.4% and 55.2%, respectively. 3) The pure thermal growth ice is predominant in marginal sea ice zone; the rafted ice and consolidated ice ridges, even second-year ice and polygonal granular superimposed ice from dynamic and thermal effects were found in front of Larsen A Ice Shelf; the thermal growth ice froze in the polynyas of Larsen A, and was transferred outwards.