Abstract: The activity coefficients of benzene and n-hexane in solutions of LiCl, NaBr and NH_4Br in methanol were measured at 298.15±0.06 K. Thecomposition of binary mixture of benzene-methanol and n-hexane-methanol was constant at each experi- mental run. Benzene or n-hexane content in equilibrium gas phase was expressed by gas chromatography and the value of activity coefficient of the component was determined by the ratio of heights of chromatographic peaks. Experimental results show that the salting out effect of benzene in methanol is smaller than that of n-hexane and the salting in factor of n-hexane by lithium ion is smaller than that of benzene, thus the mechanism of salt modified solvent was discussed preliminarily.