Phytoplankton is the primary producer of the food chain in any aquatic ecosystem, and plays a crucial role in maintaining fishery resources. Shyamsundar rail station Nala waters was investigated area. Water samples were collected and carried to the laboratory for the study. Sample after collection is properly fixed by the laboratory method. The light microscope shows different microorganisms namely Euglena, Merismopaedia, Cosmarium, Docidium, Closterium, etc. and from the species diversity calculation, we said the water body is moderately polluted.