Abstract: Some technological operational states are monitored through the analysis of trace uranium in nuclear fuel reprocessing pilot plant, so the analysis of trace uranium plays important role in the pilot plant. Time-resolved fluorescent (TRF) method is used to analyze trace uranium in the analytical laboratory of pilot plant, but the accuracy of measuring results is not very good because of the existence of some interfering ions. For accurate determination of UO²⁺₂, a rapid and simple sample pretreatment method that can eliminate the influences is established, which can meet the demand of the trace uranium analysis in nuclear fuel reprocessing pilot plant. In this method, a new type of ion exchange materials—ion exchange fiber (IEF) has been used to remove the interfering ions. The s_r is 5% (n=6) in this work. The determination results are accurate and reliable by t test (α=0.02).