Present paper deals with the analysis of diversity of Plankton (i.e., Phytoplankton and Zooplankton) and their seasonal variation of density in the Pariyat ariver, at Jabalpur district (M.P.). Four sampling stations were selected on the Pariyat river for sampling purpose. Samples were collected for a period of one year (October 2015 to September 2016) at each month of every season. Collected samples were evaluated for study of diversity of Plankton (i.e., Phytoplankton and Zooplankton) and their seasonal varaition of density. Registered Phytoplankton were belong to 35 species of 25 genera of different groups like as Chlorophyceae (12 species of 11 genera), Euglenophyceae (3 species of 2 genera), Bacillario-phyceae (5 species of 5 genera) and Cyanophyceae (15 species of 7 genera). In the study period group Chlorophyceae was dominated over rest of the Phytoplankton population. Registered Zooplankton were belong to 22 species of 16 genera of different groups like as Protozoa (3 species of 3 genera), Rotifera (12 species of 6 genera), Cladocera (5 species of 5 genera) and Copepoda (2 species of 2 genera). Among recorded Zooplankton Rotifer’s population was dominant during entire study span. It was noticed that density of Plankton was maximum in summer, minimum in rainy season and intermediate in winter season.