The intrinsic frequency of molecular-vibration of nonmetal binary hydrides is calculated with mechanic vibration theory.Both the fundamental frequency (ω₀) and the summed frequency (Σω_i) are used as molecular structural indices,and the established model:pK_a=A₀+A₁ω₀+A₂Σω_i is applied in the quantitative relation analysis.It is shown that the estimated correlation coefficient between pK_a values and the indices in the data set is larger than 0.995.Comparing the period values with the experimental values of pK_a,the mean absolute error is estimated to be less than 1.82.