Wool fabrics were treated with deep UV for 10 to 30min and then dyed with C.I. Acid Yellow 99, C.I, Acid Red 57 and C.I. Acid Blue 62. FT-IR and XPS have been used to prove the chemical composition of wool fiber surfaces. The mechanical property and colorfastness were also studied. The intencities of the peaks of C=O group at $1700^cm^{-1}$ were increased with increasing irradiation time. Relative $O_{1s},; N_{1s}; and; S_{2p}$ intensities increased considerably and oxygen was incorporated in the form of CO and COO on the fiber surface. The dye uptakes of wool fabrics dyed with three acid dyes were proportional to irradiation times and in inversely proportional to irradiation distances. It was found that the tensile strength of wool fabrics were gradually deteriorated with the UV irradiation times. The colorfastness, such as washing, light and rubbing, of UV irradiated wool fabrics dyed with acid dyes were good.