The objective of this research was to figure out the distribution of Chlorophyll-a and the water quality of Krueng Raba River in Lhoknga, Aceh Besar. The research was conducted on May 2016. Sampling was carried out using purposive sampling method at 5 stations that include the river area, estuary and inshore. The result showed the highest chlorophyll-a concentration was obtained at station 3 (estuary) and the lowest was at station 4 (inshore) with 4.55 and 0.43 µg/l respectively. Bacillariophycea dominating the river with the highest value of density of 603.28 Ind/l.