In this study, the effect of brine composition on oil recovery by waterflooding was experimentally studied. Different compositions of brine were injected in to packed one-dimensional unconsolidated limestone with Garzan crude oil (26° API) and distilled water. Ten different brine compositions, three brine mixtures are prepared and distilled water was used for injection throughout the study. The highest recovery 18.8% higher than distilled water injection) considering all the experiments was obtained by the injection of 2% KCl + 2% NaCl brine mixture.