This study focused on monthly densities and abundance of planktonic microcrustaceans (Cladocera and Copepeda) in Kırklareli reservoir, as well as their relationship with some physicochemical parameters at three different stations for the period from May 2018 to April 2019. In present study, a total of 26 planktonic microcrustaceans species, 14 from Cladocera and 12 from Copepoda were identified. The most common species in the reservoir were B. longirostris, D. pulex, D. cucullata D. galeata, D. longispina and D. brachyurum from Cladocera and C. abyssorum, C. vicinus, E. vulgaris and A. wierzejski from Copepoda. The annual mean microcrustaceans recorded during the study (24076 ind/m3) were recorded for Cladocera 67 % (16054 ± 12414 ind/m3) and Copepoda 33 % (8022 ± 5564 ind/m3). The maximum abundance of planktonic microcrustaceans were found in September (51521 ind/m3) and the minimum was found in January (2919 ind/m3). The environmental parameters measured in the reservoir was detected among the acceptable values to support aquatic life, especially the zooplankton community. The total microcrustaceans densities and abundance showed positive correlation with water temperature and Chlorophyll-a, while D. hyalina, D. cucullata, B. longirostris and C. ovalis from Cladocera and C. staphylinus, T. crassus, M. albidus, A. robustus, M. leuckarti, M. viridis and E. vulgaris from Copepoda were affected by similar environmental conditions. According to these results, we conclude that Kırklareli reservoir has a mesotrophic character in terms of the microcrustacean fauna and the physicochemical parameters.