Abstract : In that current study microalgae Chlorella vulgaris (Beijerinck) and Chroococcus minor (Kützing) ) locally isolated, were utilized in wastewater treatment to minify the pollutant parameters. Six parameter were thoughtful to determine the competence of C. vulgaris and C. minor in decrease Nitrate (NO3), nitrite (NO2), ammonia (NH3), (PO4-3), biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD) . Dry weight and optical density of microalgae were calculated daily. Wastewater samples were taken from last tank in the Al-Rustumia wastewater treating terminal before it is discharged into the Diyala River. In general, it has been found that the mean values of examined variables were varied significantly in terms of algae species and times. C. vulgaris gave better removal result of nutrient and COD, BOD than C. minor. The results showed removal 100% after 4-5 days of treatment of both ammonia and phosphorous at the same period , removal observed of COD was to be 84.8% - 71% and was recorded the removal BOD 93%-67.2% for C. vulgaris and C. minor , respectively. In addition, that dry weight and optical density have increased significantly as the testing time. Results confirm that wastewater as a cost efficient growth medium for lipid and higher biomass production accompanied for the nutrient removal efficiency of microalgae which in turn reduces Eutrophication.