The Haruku Strait in the Central Moluccas is a potential marine resource located eastern Indonesia. Small pelagic fishes have been noted in abundance in the waters of this strait. Their abundance is mainly associated with the ample amount of plankton organisms serving as food for the former. To address the abundance of phytoplankton in Haruhu Strait, a study was carried out in September 2022. Sampling was achieved using a sample bottle from a depth of 1 meter. After that, the sample was filtered with a Kitahara net. Nineteen genera of phytoplankton were found in Haruku Strait during the study period. The phytoplankton abundance varied between 4,5 x 102 – 1,65 x 103 cells/l. Phytoplankton consists of Bacillariophyceae (Diatom) with 63% of the total genera, Dinoflagellata with 32 % of the total genera, and Cyanobacteria with 5%, while Chaetoceros, Rhizosolenia, Gonyaulax, Coscinodiscus, and Ceratium were the predominant phytoplankton genera in this area. The distribution pattern forms 8 groups.