The characteristies of K⁺ adsorbing-desorbing kinetics of five loessial soils were studied by the liquid flow technique. The results indicated that:①K⁺ adsorption and desorption equilibrated in 16-24 and 24-60 min, respectively, and the time and the capacity of K⁺ equilibrium adsorption were closely related with soil clay content and CEC;②there was a linear relationship between the K⁺ adsorbing-desorbing velocity and the reaction time lnt, and the slop of reaction velocity regression equation and K⁺ desorbing percentage regression equation, the original reaction velocity and the original desorbing percentage were closely related with soil clay and CEC;③First-order and Elovich equations were the best modles for K⁺ adsorption and desorption, respectively;④it is demonstrated that there were dif ferent energy level sites of K⁺ adsorption at the surface of soil colloid by the fast, medium and slow reactions of K⁺ adsorbing-desorbing;and ⑤the K⁺ adsorption and desorption were controlled by the diffussion process.