As one of the agricultural wastes，the rice straw can be served as a raw material that adsorbed K+.The method of equilibrium adsorption was adopted to study the adsorbed rule of K+ on the rice straw under the different influencing factors.The results showed that:(1)When the initial concentration of K+ was low(0~40 mg/L)，the temperature raising promoted the effect of rice straw releasing K+ to restrain the sorption，on the contrary，when the concentration of K+ was increased to the range of 40~1 000 mg/L，the adsorption of K+ on the rice straw was enhanced by the increased temperature.The phenomenon of multilayer adsorption occurred，the process was endothermic and spontaneous，and the disorder in the solidliquid interface was also increased after the sorption;(2)The surface of rice straw carried a large number of Ocontained functional groups，whose negative charges were enhanced with the increasing of pH value.The increased pH value enhanced the adsorbed amount of K+ on the rice straw through strengthening the electrostatic adsorption;(3)The chemical bonding was dominated in the adsorption mechanism.In the aspect of compressing the thickness of double electrode layer and weakening the electrostatic interaction between adsorbate and adsorbent，the ability of Na+ was more than NH+4;(4)The appropriate mass ratio of rice straw/K+ was 5∶2;(5)Under the temperature condition of 298 K，if the contact time from the both was more than 420 min，the net adsorption was possibly happened，however，at relatively higher temperature(318 K)，the contact time must be more than 1 380 min.In describing the dynamic adsorption between rice straw and K+，the best fitting results was obtained by a twostep fitting algorithm.The rule mentioned above not only provided a scientific formula based on a reasonable allocation of straw and K+，but also gave a technical support and theoretical reference for developing a new organic fertilizer，in which the straw and K+ could serve as the main raw materials.