he objective of this study is to understand the calcareous nannoplankton response to past environmental changes in the Strait of Hormuz during the Holocene. Calcareous nannoplankton is well abundant in the living phytoplankton community and a key component of the marine sediments. Due to its distinct reaction to environment changes and its good preservation potential, it is well suited for paleoceanographic reconstructions. Therefore, the study of the calcareous nannoplankton is indicative for paleoceanographic changes in the Strait of Hormuz. For this purpose, 15 samples of surface sediments of the Strait of Hormuz are selected and 27 species and 16 genera are introduced. In this study, we have observed 3 groups of calcareous nannofossils. These groups included abundant taxa, rare taxa and reworked taxa. We study all samples of the Strait of Hormuz for detecting the total organic carbon content.They have shown that there is a relationship between TOC, CaCO3 and productivity of calcareous nannofossils. Some samples include high TOC and CaCO3 values and they are correlated to high productivity of calcareous nannofossils. Also due to dilution, some samples showed a negative relationship between TOC and CaCO3 . Some specific element compositions of this region were analysed and then we studied the relationship between them and relative abundances of calcareous nannofossils. Some elements like Ba, Cu and Zn reveal a close relationship to fertility of calcareous nannofossils and they are highly enriched in the nutrient-rich waters of strait of Hormuz. Ba, Cu and Zn content and relative abundances of nannofossils were high in the near shore of Strait of Hormuz. The distribution pattern of the Si content shows a persistent minimum in this area. This element have shown a negative relation to productivity of calcareous nannofossils. Relying on information, we can conclude the coast of Strait of Hormuz is affected by upwelling and it is an appropriated environmental aspect of nutrients and productivity

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