Six water stations were chosen along the lower reach section of AlKebir ALShimaly river and some of it's tributaries, differing in their biotic and abiotic features. Water and animal samples were collected bimonthly during spring, summer & autumn and monthly during winter during the period 25/8/2013 – 26/8/2014. Seventeen species of freshwater molluscs were identified in all stations, fifteen belonging to Gastropoda (6 of Prosobranchia & 9 of Pulmonata) and 2 belonging to Bivalvia, one of it (Corbicula fluminea) was recorded for the first time in Syrian Arab Republic. We focused on in this study on the station ( Mafraq Quesmeen) that we studied it's chemical and physical properties of the water and we identified 11 mollusc species and the most frequency of it was Melanopsis praemorsa and it's frequency rate was 46.48% and it was the most constant in all continuous samples and it was 100%