The properties of desorption dynamics of sulfate and the effects of pH and temperature in four red soils were studied. The results showed that the maximum desorption was 70%-94%. The data of desorption curves can be fitted well by the Elovich equation and two-constant kinetic equation. The amount of desorption increased and velocity of desoiption slowed down with the increase in pH The amount of desorption increased and velocity of desorption speeded up with the increase in temperature. The activation energy calculated according to Arrheius equation was 23.35 kJ mol^-1.