In the previous paper(Ⅲ), the following equation of solvent effect in organic chemistry was suggested:Where Ei is a physical or chemical property of the substrate in the solvent i and E0 is that in n-hexane. Ai and Di are constants of electron acception and donation effect of the solvent i respectively. VAi and VDi are constants of electron acception and donation space effect of the solvent i respectively, a and d are the sensitivities of E of the substrate vs the change of Ai and Di. Va and Vd are the constants of electron acception and donation space effect of the substrate respectively. In IR spectra E couJd be substituted by the wavenumber (v). Ai and VAi have been estalished for 18 organic solvents (n-C6H14, n-C7H16, cyclohexane, CC14, Ph-Me, ClCH:CCl2, Et2O, CHCl3, C6H6, CH2Cl2,ClCH2 CH2Cl, Ph-NO2, THF, 1,4-dioxane, Et-NO2. MeCO2Et, Me-NO2, Me-CN).In this paper Di and VDi have been established for these solvents. The equation also has been tested by the vC-X (X=Cl, Br) of five alkylhalides (t-BuCl, ) n-C5H11Cl,t-BuBr, Et-Br, EtC(H)BrMe) and YC=O of three carboxyl compounds (t-BuCOMe,Me2CO, MHB) and seven organotin compounds [(Ph2MeSiCH2)3SnO2C-C6H4-X-p (X=H-, CH3-, CH3O-, NO2-, F-, Cl-, I-)].The relationship (u = ρ·σ + vo) between vC=O of organotin compounds and Hammett constants (σ) of the substituted groups in different solvents was studied and a relationship bewteen ρ and Ai, VAi ) Di, VDi of the slovents was found.