用电势法测定了298.15K以及I为0.1、0.5、1.0、1.5、2.0、2.5和3.0 mol/kg时,NaBr在混合电解质溶液NaBr+NaAc+H_2O中的活度系数.实验结果用Harned、SRJ和Pitzer方程拟合,得到各种方程的相互作用参数,由拟合的标准偏差得知,Pitzer方程的拟合精度略好于前2个方程.用Pitzer混合参数θ_(Br-Ac)和ψ_(Br-Na-Ac)计算了NaAc在该混合体系中的活度系数和体系的过量Gibbs自由能. The activity coefficient of NaBr in mixed electrolyte solution NaBr + NaAc + H_2O was measured by potentiometry at 298.15K and 0.1,0.5,1.0,1.5,2.0,2.5 and 3.0 mol / kg, respectively. The experimental results were obtained with Harned, SRJ And Pitzer equation were fitted to obtain the interaction parameters of various equations. From the standard deviation of fitting, the fitting accuracy of Pitzer equation was slightly better than that of the first two equations. Using the Pitzer mixing parameters θ_ (Br-Ac) and ψ_ (Br-Na-Ac) to calculate the activity coefficient of NaAc in the mixed system and excess Gibbs free energy of the system.