Abstract: Based on the data and information of 22 surface sediment samples obtained from Prydz Bay during China's 29th Antarctic Expedition, the diatom assemblages in the study area and the spatial distributions of some principal diatom species were analyzed. A total of 29 diatom species, belonging to 12 genera, were identified from the surface sediments. Fragilariopsis curta and F. kerguelensis were the dominant species. The relative percentage of 4 sea-ice diatoms, F. curta, F. cylindrus, F. ritscheri, and F. separanda, decreased gradually from inside of the bay to the open ocean. Ice-edge diatoms, such as Thalassiosira antarctica and Porosira glacialis, occupied with high percentage and decreased from the middle region of the Prydz Gyre to the outside. On the contrary, F. kerguelensis, Paralia sulcata and Azpeitia tabularis increased gradually within the bay to the open ocean. A Canonical Correspondence Analysis (CCA) was used to study the relationship between diatoms and environmental factors. The conclusions were drawn: the results of CCA were consistent with the ecology of principal diatom species. F. curta, F. separanda, F. cylindrus, and F. ritscheri could be used as low temperature indicator species. Meanwhile, P. glacialis and T. antarctica might be used as low salinity indicator species. The exact relationship between environmental factors such as sea surface temperature, sea surface salinity et al., and the surface diatom were analyzed which provides the data support for subsequent establishment of diatom-environment transfer function and quantitative reconstruction for the changes of these environmental factors in the past.