A measurement method of Ta contents in U-Ta alloy by energy dispersive X-ray fluorescence (EDXRF) was introduced. Dissolved by acid, coated on filter paper and prepared the filter paper samples, the Ta contents in U-Ta alloy samples were determined by EDXRF. The method is simple, rapid, accurate, and applicable to the determination of Ta content in 1%-6% U-Ta alloy samples. The relative standard deviation (RSD) of this method for the U-Ta alloy sample of 1.5% tantalum content is less than 0.6%, while for the U-Ta alloy sample of 5% tantalum content is less than 0.3%.