During the production of titanium dioxide by sulfuric acid process,the insoluble solid phase of acidolysis of ilmenite is the main factor limiting the productivity.In order to reduce its influence,the solid phase of acidolysis was analyzed by X-ray diffraction（XRD）.The effects of the main reaction factors including the ratio of acid to ore,the concentration of reation acid and the initiation temperature etc.on the solubility of solid phase were compared.The XRD analysis showed that the process of sulfate of titanium produced by the titanium concentrate pyrolysis didn′t form a crystal,and the dissolution of the solid phase was only a physical process.Comparison of the main reaction factors of titanium concentrate acid solution showed that the factors affecting the difficulty of dissolution of titanium concentrate acid solution from large to small were the reaction acid concentration,initiation temperature,and the ratio of acid to ore was no effect.With the increase of the reaction acid concentration,the main reaction rate was accelerated,the dehydration rate was increased,the binding water content in the sulfate of titanium was reduced,the solubility was reduced,and the solid phase were harder to dissolve.The acid mass fraction of the optimal reaction during the acid hydrolysis process was 82%~83%,and the initiation temperature was 145 ℃.