根据Donnan膜平衡模型及外推法提出弱碱性阴离子交换树脂本征解离常数的测定方法。并测得大孔丙烯酸系弱碱性阴离子树脂D705的本征解离常数的负对数pK_b~(int)为3.72士0.04,结果表明,Marinsky在测弱酸性阳离子树脂的pK_a~(int)时,引入交换剂相中H~+及Na~+的活度系数相等的假定并非必要。 According to the Donnan membrane equilibrium model and the extrapolation method, the determination method of intrinsic dissociation constant of weakly basic anion exchange resin was proposed. The negative logarithm pK_b ~ (int) of the intrinsic dissociation constant of the macroporous acrylic weakly basic anion resin D705 was measured to be 3.72 ± 0.04. The results showed that when Marinsky measured the pK_a ~ (int) of the weakly acidic cation resin , It is not necessary to assume that the activity coefficients of H ~ + and Na ~ + in the exchanger phase are equal.