Abstract: Time-resolved fluorescence (TRF) method is most often used to analyze trace uranium in complex matrix. But the accuracy of measurement is not very good because of the existence of some interfering ions, so sample pretreatment is needed. Solvent extraction method is mainly used currently, which has slow analysis speed (40 min for each sample). For fast and accurate determination of UO²⁺₂, a sample automatic pretreatment equipment that can eliminate the influences is developed, which can meet the demand of the trace uranium analysis in complex systems. The equipment can greatly improve the analysis speed -(5 samples per hour), saving the cost of human resource.