系列文章的第一部分总结了矩形截面高层建筑横风向脉动风力的基本特征。本文在此基础上，采用非线性最小二乘法，以风场类型及厚宽比为基本变量，对横风向脉动风力根方差系数、竖向相关系数以及功率谱密度进行拟合，得到横风向脉动风力的闭合求解公式。最后通过与试验结果的比较，验证了这些公式的精度。运用这些公式，可较为方便地计算矩形截面高层建筑的横风向脉动风力。

The basic characteristics of across-wind fluctuating wind forces acting on rectangular super-tall buildings have been described in PartⅠof the series of papers. In present paper, mathematical model of across-wind fluctuating wind forces are investigated based on the results shown in PartⅠof the papers. Using the nonlinear least-squares method, formulas for the RMS force coefficients, vertical correlations and power spectrum densities (PSDs in short) are fitted as the functions of side ratio of building cross-section and terrain category condition. By comparison with the original test results, the precision of the present formulas are finally verified. These formulas for the across-wind fluctuating wind forces could be applied to wind resistance design of rectangular super-tall buildings.