In a Tween 80-(NH4)2S04-xylenol orange liquid-solid extraction system, absorption spectra of complexes of metal ions in extraction phase with xylenol orange as the extractant were investigated. Compared to xylenol orange spectra, the maximum wavelength of complexes of Cu(II), U(VI) and Ce(IV) shifted to the red by 20-30 nm, while that of La (III) did not. With different acidity, quantites of xylenol orange and salt, and surfactant, the efficiencies of Cu(II), La(III), U(VI) and Ce(IV) metal ions were discussed. The results indicated that the complexes of Cu(II) and U(VI) with xylenol orange were almost completely extracted by the Tween-80 phase, that of Ce(IV) was partially extracted, while that of La(III) was not extracted from the aqueous solution of pH 6.0. The extraction separation of La(III) and U(VI) was carried out by controlling the solution acidity.