Abstract: This paper reports a new trichloroarscnazo (TCA) chelating agent-loaded resin and its preparation and properties.It was found that TCAresin had a high selectivity for thorium and its stability,selectivity and regeneration were superior to those of common loaded resin reported in literature.Satisfactory results were obtained when this resin super-short column (φ0.8×2cm) was applied to the separation and preconcentration 1-100 ppm trace amounts of thorium from one gram of high-purity rare earths and uranium and ppb trace amounts of thorium in water.TCAresin can be repeatedly used after regeneration.