The catalytic action of vanadium on the reaction between benzidine and potassium chlorate has been studied and therefrom a sensitive and convenient method fox the detexmination of traces of vanadium has been proposed.The reaction rate between benzidine and potassium chlorate is very slow.If micro amounts of vanadium and small amounts of oxine are added to the test solution at pH 2.5-3.0,and heat for some time at 100℃ then the vanadium shows a strong catalytic action on the above reaction.