Paddy soil derived from yellow-brown soil, rich in organic matter, was used to extract clay particles < 2 μm, half of which was deprived of organic matter, and then prepared into samples saturated with Na⁺,K⁺,NH₄⁺,Ca²⁺, Cd²⁺ and La³⁺ cations, separately. Effects of organic matter (OM) on interactions between cations and soil clay particles were investigated with the aid of the suspension Wien effect. It was found that threshold electrical conductivity was higher in the suspensions of original soil than in the suspensions of OM-removed soils. In all the suspensions, except for Na⁺ -saturated one, the rate increasing electrical conductivity of the OM-removed soil suspensions with field strength in the range > 50~100 kV cm^-1 was apparently higher than that of the original soil suspensions. OM increased the mean free binding energies of all the cations other than Na⁺, with the effect being the most significant on Ca²⁺, about 0.57 kJmol^-1, and being the least on Cd²⁺, around 0.03 kJmol^-1. In all the soil suspensions, binding energies of various cations followed the sequence of Na⁺ < K⁺ ≈ NH₄⁺ < Ca²⁺ ≈ Cd²⁺ < La³⁺.OM reduced the mean free adsorption energies of all the cations except Na⁺. The effect was significant for NH₄⁺ at field strengths > 70 kV cm^-1, for K⁺, Ca²⁺ and Cd²⁺ at field strengths > 50 kV cm^-1 and for La³⁺ at field strengths > 70 kV cm^-1, and the difference got more obvious with increasing field strength. OM made it more difficult for cations adsorbed on clay particles to get released into the solution. Stripping intensities of the cations except Na⁺ were distinctly higher in the suspension of OM-removed soil than in the suspension of original soil, with the difference △Is following the order of K⁺ < NH₄⁺ < La³⁺< Ca²⁺ < Cd²⁺, which indicated that OM made Cd²⁺ adsorbed on clay particles most difficultly strip off. In Na⁺ and K⁺ saturated soil clay particles, OM made zeta potential move towards positivity by 40 mV, but in clay particles saturated with NH₄⁺,Ca²⁺,Cd²⁺and La³⁺, towards negativity by 17 ~ 36 mV.