Abstract: According to the quantitative reaction of U(Ⅳ) and Fe(Ⅲ) in H_2SO_4 aswell as the relation between current and concentration of substance detected, U(Ⅳ) has been. determinated indirectly by measurement of the electrolysis currentof residual Fe (Ⅲ). The columniform electrode used is made of glass carbonparticles. At the range of U(Ⅳ) from a few micrograms to 40μg, the linear relation isexcellent. The relative standard diviation is within ±5%. The interference of Fe(Ⅱ), Ti(Ⅳ) and U(Ⅵ) is neglible but of Ti(Ⅲ) is sireous. This method hasbeen successfully applied in the determination of actual uranium samples (bothout line and on line). Main advantages of this procedure are rapid, simple, small amount of sample(only at microgram level) and easy to realize automation, able to use for on lineor process analysis.