The Banda Sea is one of Indonesia's deep-sea ecosystems with complex oceanographic dynamics influenced by monsoons and upwelling phenomena. Phytoplankton, as primary producers, play a crucial role in the marine food chain and overall water productivity. This study aimed to analyze the composition, distribution, and abundance of phytoplankton in the Banda Sea and to evaluate its implications for marine productivity. Sampling was conducted at 18 stations at a depth of 1 meter using a Nansen bottle, followed by filtration with a Kitahara net. Phytoplankton identification and quantification were carried out using a microscope and cell counting methods. The results showed that phytoplankton were dominated by Bacillariophyceae (61%), followed by Dinophyceae (33%) and Cyanophyceae (6%). Chaetoceros was the most abundant genus, followed by Rhizosolenia, Bacteriastrum, and Trichodesmium. Cluster analysis using the Bray-Curtis similarity index grouped the study stations into five clusters based on phytoplankton community similarity. The dominance of diatoms indicated that this area has high primary productivity, supported by upwelling that transports nutrients from deeper layers to the surface. The findings contribute to understanding the ecological dynamics of the Banda Sea and provide insights for sustainable fisheries management.