In order to evaluate the effect of different levels of humic acid on some quantitative and qualitative traits of cotton a factorial field experiment in a randomized complete block design with three replications was conducted in Kashan under salinity soil condition in 2013.Treatments included three cotton cultivars of Varamin, Line 43200 and Khordad as first factor, and six foliar ‌treatment included without humic acid and chemical fertilizer‌ (T₁), without humic acid with chemical fertilizer (T₂), 3 l/ha humic acid without chemical fertilizer (T₃), 1 l/ha humic acid with chemical fertilizer (T₄), 3 l/ha humic acid with chemical fertilizer (T₅), and 6 l/ha humic acid with chemical fertilizer (T₆).The results showed that humic acid significantly increased oil and protein content, yield, seed yield, fiber yield and 1000 seeds weight. In T₅ treatment, gin, lint, and grain yields, 1000-grain weight, and oil content increased by 32.74%, 31%, 33.69%, 5.32%, and 2.7%, respectively. Using 3 liters of humic acid without the application of chemical fertilizer increased seed protein yield by 63.4%.