Algae sometimes referred to as the phytoplanktons, inhibit the upper sunlit layer of almost all freshwater ecosystems and form part of the lentic system biota. They are a highly diverse group of organisms that have important functions in aquatic habitats. The present study was conducted to assess the relationship between physico-chemical parameters and phytoplankton assemblages of Dora beel of Assam, India. A data set of environmental parameters and algal bloom occurrence, density and composition was analyzed seasonally (i.e., monsoon, post-monsoon, winter and pre-monsoon). Statistical treatment of data between phytoplankton species and seasons and the water parameters and seasons in a year indicate that the phytoplankton cell count, diversity and distribution of phytoplankton in the Dora beel is influenced both by the variabilities of season and water parameters.