In order to simulate the mechanism of the main organic acids in root exudates (oxalic acid and citric acid) releasing potassium from soil, the difference in ability to enhance the available potassium in cinnamon soil of H+ and organic ligands was studied and the chemical mechanism was analyzed through an experiment in which soil samples were continuous cultured. The results showed that, soil samples were cultured for 25 days in different reagents, the available potassium content in each treatment was higher after adding oxalic acid (157.65 mg/kg) and lower after adding sodium citrate (98.49 mg/kg), the differences among the varieties were significant. There was no difference in acidification and complexation under the same add concentration. The research suggested that available potassium releasing mainly depend on acidity of solution when the solution with high concentration but complexation of organic ligands turned dominant as the solution concentration was low. The process of available potassium releasing from soil is a cyclic process in which soil was acidified after complexed by organic acids. It should be considered as a theoretical basis how to increase the content of matter with complexation in rhizosphere soil for fertilization and breeding.