The photoyellowing and poor UV-protection ability of silk, wool and nylon fabric can be improved through the anti-UV finishing with UV-absorbers. This study is concerned with the adsorption properties of a water-soluble benzotriazole UV-absorber on silk, wool and nylon. It was found that the adsorption kinetics of the UV absorber on the three fibers followed the pseudo second-order kinetic model and the rate constant indicated a faster adsorption rate for UV absorber on silk than those for wool and nylon. The activation energies for the adsorption process on silk, wool and nylon were found to be 49.74, 63.92 and 78.21 kJ/mol, respectively. The adsorption of the UV-absorber on silk and wool had the characteristics of low affinity constant and high saturation value whereas that on nylon showed a small saturation value with a remarkably high affinity constant. The electrostatic interactions between the positively charged amino groups in fibers and the anionic sulfonate groups in UV absorber have an important role in the adsorption of UV absorber.