T The java trench is the product of subduction between the indo-australian and eurasian plates and reaches depths of up to 7,000 m. this setting creates a complex deep-sea environment shaped by tectonic dynamics, sedimentary processes, and biogenic supply. this study aims to characterize deep-sea sediments of the java trench using calcareous nannofossils as the primary proxy to infer depositional conditions and changes in the carbonate compensation depth (ccd). sampels were obtained during the china–indonesia joint java trench deep-sea expedition under the supervision of brin and idsse. sampling was carried out at multiple sites along the trench using gravity coring. methods included smear-slide preparation, morphological identification of nannofossils under a polarizing microscope at 1,500× magnification, and quantitative counts of at least 200 specimens per sampel. analyses focused on abundance, diversity, and preservation of nannofossils. a total of 25 genus and 64 species were identified. depth-interval analyses reveal distinct variations in abundance and taxonomic composition spanning the cretaceous, paleogene, and neogene. because reworked specimens are abundant, the oppel method was applied to interpret bioevents; the assemblages indicate biozones nn14–nn16 (early pliocene), with discoaster brouweri and discoaster surculus recognized as key species. numerous older reworked taxa were also recorded, reflecting redeposition by mass-flow processes (e.g., turbidites) and tectonic activity. these results indicate that deep-sea sediment characteristics in the java trench are governed by the interplay of subduction-zone tectonics, oceanographic dynamics, and biogenic sedimentation. the presence and preservation of calcareous nannofossils below the regional ccd reflect rapid sediment supply and complex depositional processes that permit partial carbonate preservation in the deep marine.