Abstract: The current research on the sediments of the Southwest Indian Ridge(SWIR) mainly focuses on the surface sediments of the flank of the ridge, but lack of research on its ridge axis restricts the in-depth understanding of the sediment sources and sedimentary environment in this area.Based on the major element, trace element, REE and Y assay of a sediment core(GC03) collected from SWIR 49.58°E during Chinese DY-49 Cruise, the material source and sedimentary environment of the sediments in the study area were discussed.The results show that the bulk samples are enriched in CaO, LOI and Sr, indicating that calcareous biodeposition is dominant and mixed with basalt debris.The content of the ΣREY is low, with average value of 54.3×10^-6, and the chondrite-nomalized REY distribution patterns show the enrichment of LREE compared to HREE and significant negative Ce and Eu anomaly.The enrichment of metal elements such as Cu、Zn、Fe and Co, and low 100*Al/(Al+Fe+Mn)value characterizing samples from Layer L2(83-87 cmbsf)reveals the presence of a hydrothermal component input.The Ce_anom value and V/(V+Ni)-U/Th discriminant diagram indicate that the study area is generally a stable oxidized environment except for reduction characteristics exhibited from partial samples.