Abstract: Ion exchange resin ean dissociate some minerals of low solubility,but the method has not been widely used so far.Phosphate rocks are composed of compounds with Jow solubility.In suspension of compounds,chemical equilibrium between the solid phase and saturated solution may be established.The dynamic equilibrium depends on ion concentration of reaction products at specific temperature.When a hydrogenous 732 cation exchange resin exists in hot water,the resin adsorbs cations of the dissociated compounds,the anions of the dissociated compounds and the replaced H+ combinate into soluble compounds in form of ionic state.The process continues and establishes new equilibrium uninterruptedly till the minerals of low solubility are entirely dissociated.The author added 732 strong acid cation exchange resin into hot water and dissociated phosphate rocks successfully.The content of fluorine was determined by spectrophotometry quantitatively.In place of the traditional method of acid-alkali fusion and separation of coexisted ions by distillation,the ion exchange resin method here has avoided laborious operation in determination of fluorine.The author applied a magnetic stirring instead of the shaking method introduced by Schafer (1963) and a thermostatic water bath to control the solution temperature,which simplified the heating and temperature controlling procedure.The advantages of this method reported in this paper are simplicity of equipment,easiness of operation,good repeatability and efficiency.