Polyvinyl alcohol amidoxime (PVAAO) chelate fiber prepared in our laboratory is a good adsorbent. Comparing with other adsorbents, it has many advantages, such as higher hydrophilicity, better adsorbability and easier synthesis. In this work, the synthesis course, structure and properties of PVAAO fiber have been studied by the means of FT-IR, SEM, ESR, and TG. The structural changes of the fiber associated with adsorbed copper ions have also been investigated using ESR, FT-IR, and XPS. In addition, chelating mechanisms of the fiber-adsorbing copper ions have been discussed.