Although role of salicylic acid (SA) in enhancement of salinity tolerance of plants has been well shown, more researches are needed for better understanding of its physiological mechanisms. In this experiment, the effect of different SA concentrations (0, 0.5, 1.0, 1.5 and 2.0 mM) was examined on biochemical attributes and grain yield of barley cv. Nosrat under non-saline and saline conditions (2 and 12 dS.m^-1, respectively) during 2012-13 and 2013-14 growing seasons at the National Salinity Research Center, Yazd, Iran. Salt stress enhanced soluble proteins content, free proline, malondialdehyde and electrolyte leakage by 22.1%, 147.7%, 87.2% and 102.9%, respectively. However, membrane stability index as well as concentrations of chlorophyll a and b reduced by 33.2%, 31.4% and 59.3%, respectively. Salt stress also decreased grain yield by 34.2% and 40.9% in the first and second year, respectively. Salicylic acid reduced the negative effect of salt stress on grain yield, therefore, SA foliar application decreased the rate of grain yield reduction under saline condition from 42.1 in no-SA to 27.3% in 1.5 mM in the first year and from 43.7% in no-SA to 33.8% in 1.0 mM in the second year. This mitigation could be related to biochemical attributes, as SA at different concentration levels enhanced soluble proteins content, free proline, concentration of chlorophyll a and b and carotenoids as well as membrane stability index, and reduced malondialdehyde and electrolyte leakage. It can be concluded that SA had better effect up to 2.0 and 1.0 mM under non-saline and saline conditions, respectively. In Genral, SA with reducing negative impact of salt stress on biochemical attributes could improve salinity tolerance and increase grain yield of barely cv. Nosrat.