This study aims to investigate the phytoplankton dynamics (distribution, composition) and their relation to water quality parameter in Ismailia canal and Abbassa fish farm (inlet, outlet and the fish ponds).The study was carried out from April, 2014 to May, 2015. Physical, chemical parameters and phytoplankton estimation were measured in situ and laboratory. The results showed that, the physico- chemical parameters of water were significantly varied among different seasons and the studied sites. Phytoplankton communities are represented by eight phyla namely; Chlorophyta, Cyanophyta, Euglenophyta, Bacillariophyta, Chrysophyta, Dinophyta, Cryptophyta and Xanthophyta. Their major number (22724 Org./ml) was detected at the fishponds (site C), while their minor number (9374 Org./ml) was detected at the main feeder (MF), (site A). Chlorophyceae was the predominant class at all studied sites except at (MF) where; Bacillariophyceae occupied the first predominant position. Results demonstrated that occurrence of 247 taxa of phytoplankton at (MF), 273 taxa at (inlet), 304 taxa at fishponds and 292 taxa at outlet. Also, Shannon and Weaver diversity index (H^-) was studied and the results showed that the mean range of the phytoplankton diversity index (H^-) was low (< 2.0) at all the studied sites and this is indication of moderate pollution. It is concluded that, both seasonal variations and physico-chemical parameters of water have great impact on phytoplankton dynamics and its biological diversity.