A method of preparing titanium solution comprising: A. mixing 55-98%wt sulfuric acid with enriched titanium hydrochloric acid extract residue in the mass ratio of 1.4-1.9 to 1, heating the mixture to 130-220 °C, wherein the heating is controlled to maintain the reaction and reaction temperature; B. obtaining a viscous solid mixture; C. curing the obtained mixture at 140-220°C for 1-4 hours followed by cooling down the mixture and then either - adding warm water which is 2-3 times of volume of sulfuric acid; or - adding 60-70°C 20%wt sulfuric acid to dissolve the solids obtained after curing, cooling, and adding water to give a TiO 2 concentration of 200 g/L; D. stirring the solution for 5-240 more minutes until the solid mixture is dissolved and filtering the solution to obtain titanium solution; and wherein, the enriched titanium hydrochloric acid extract residue in step A consists of loose and porous residue obtained after removing iron from crystal lattice of ilmenite (FeTiO3) by hydrochloric acid leaching as well as the metatitanic acid aggregates, and wherein the extract residue is prepared by following the procedures: a. leaching ilmenite by hydrochloric acid to obtain a solid; b. drying the solid until the water content is no more than 20%wt, wherein the extract residue can be dissolved by sulfuric acid, is white, light yellow or light grey particle or powder, comprises 65-97%wt amorphous TiO 2 and less than 8%wt iron, and has a specific gravity of 2.9-3.6. A. mixing 55-98%wt sulfuric acid with enriched titanium hydrochloric acid extract residue in the mass ratio of 1.4-1.9 to 1, heating the mixture to 130-220 °C, wherein the heating is controlled to maintain the reaction and reaction temperature; B. obtaining a viscous solid mixture; C. curing the obtained mixture at 140-220°C for 1-4 hours followed by cooling down the mixture and then either - adding warm water which is 2-3 times of volume of sulfuric acid; or - adding 60-70°C 20%wt sulfuric acid to dissolve the solids obtained after curing, cooling, and adding water to give a TiO 2 concentration of 200 g/L; - adding warm water which is 2-3 times of volume of sulfuric acid; or - adding 60-70°C 20%wt sulfuric acid to dissolve the solids obtained after curing, cooling, and adding water to give a TiO 2 concentration of 200 g/L; D. stirring the solution for 5-240 more minutes until the solid mixture is dissolved and filtering the solution to obtain titanium solution; and wherein, the enriched titanium hydrochloric acid extract residue in step A consists of loose and porous residue obtained after removing iron from crystal lattice of ilmenite (FeTiO3) by hydrochloric acid leaching as well as the metatitanic acid aggregates, and wherein the extract residue is prepared by following the procedures: a. leaching ilmenite by hydrochloric acid to obtain a solid; b. drying the solid until the water content is no more than 20%wt, wherein the extract residue can be dissolved by sulfuric acid, is white, light yellow or light grey particle or powder, comprises 65-97%wt amorphous TiO 2 and less than 8%wt iron, and has a specific gravity of 2.9-3.6. a. leaching ilmenite by hydrochloric acid to obtain a solid; b. drying the solid until the water content is no more than 20%wt,