Abstract: The extraction of titanium（Ⅳ） from hydrochloric acid solutions by tributylphosphate（TBP） and decanol was studied. The results demonstrate that the extraction ratio of titanium（Ⅳ） increases with the increased concentration of TBP, decanol and chloride ion. Titanium（Ⅳ） exists as TiCl₄（TBP）₂ Decanol in the organic phase during the extraction of lower concentration titanium（Ⅳ）, while it changes into TiCl₄TBP（Decanol）_1/2 for the extraction of higher concentration titanium（Ⅳ）. TBP-decanol-titanium with higher concentration can aggregate into reversed micelles in the organic phase, according to the measurement of average hydrodynamic radius, electrical conductivity and IR spectra of the organic phase as well as the synergistic extraction effects investigation. It means that the extraction of titanium（Ⅳ） with higher concentration from hydrochloric acid solutions by TBP and decanol progresses as a combined mode of solvent extraction and reversed micelle extraction. The extraction rate is fast and the equilibrium can be obtained in 10 min. At the same time, calcium（Ⅱ）, magnesium（Ⅱ） and aluminum（Ⅲ） in hydrochloric acid solutions cannot be extracted. The extraction isotherm for titanium（Ⅳ） in 8 mol·L^-1 hydrochloric acid solutions was plotted with the composite extraction agents. And the stage of countercurrent extraction was explored.