Elovich, parabolic diffusion, power function and exponential equations were used to desoribe K desorption kinetics of 12 soils in a constant electric field of EUF. Results showed that the Elovich, parabolic diffusion and power function equation could desoribe K desorption kinetics well, owing to the high correlation coefficients and low standard errors; but the exponential was not suitable to be used in this experiment, due to the relatively low correlation coefficients and relatively high standard errors. This paper established successfully the relationships between the kinetic equations and the barley responses to K fertilizer in the field experiments and K status of soils, the contants (slope or intercept) of Elovich, parabolic diffusion and power function equations were highly significantly or significantly correlated to the soil exchangeable K, relative yeild of barley(NP×100%/NPK) and K uptake by bariey in the NP plot. It was suggested that the kinetic equation constants could be used to evaluate K-su pplying power of soil.