On the chosen six sampling points on Aksu River, 80 taxa belong to Bacillariophyta, 40 taxa belong to Chlorophyta, 15 taxa belong to Cyanophyta, 2 taxa belong to Euglenophyta and 1 taxon belong to Rhodophyta, total 138 taxa were determined. The ephilitic algae biodiversity is parallel to the water quality on Aksu River. BOI(5) is the most effective parameter on the biodiversity of epilithic algae. Ammonium nitogen, ortophosphate, nitrate nitrogen, sulphate, and chloride fallow this. The dominant species differ according to sampling points. On the I. sampling point the dominant takson was Achnanthes lanceolata on the II. and III. sampling points the dominant takson was Nitzschia palea and A. lanceolata was not found on this sampling points. On the W. sampling point Cocconeis pediculus, V sampling point Navicula gracilis and on the VI. sampling point Diatoma vulgare were dominant species.