BACKGROUND: Studying the characteristics of rare earth elements in uranium ore can determine the source of the ore-forming fluids, the mineralization environment, and the physical and chemical conditions. It is particularly important to accurately determine the content of rare earth elements in uranium ore. At present, rare earth elements are mainly determined by inductively coupled plasma-mass spectrometry (ICP-MS). High-pressure closed aciddissolution is commonly used. The open acid dissolution method is rarely used because perchloric acid is routinely used to dissolve samples, and the temperature is relatively low, which may cause incomplete decomposition of some samples. OBJECTIVES: In order to solve the problem that the rare earth elements have contents lower than real values in open acid dissolution. METHODS: The tetracid system of nitric acid-hydrofluoric acid-perchloric acid-sulfuric acid was used in the open acid dissolution method. ICP-MS with Rh as internal standard was used to determine 15 rare earth elements in uranium ore. RESULTS: The relative standard deviation (RSD) of the 15 rare earth elements was between 0. 54% and 5. 98%, and the recovery was between 96. 0% and 106. 0%. Applying to national rock standard materials (GBW07103, GBW07104, GBW07122), the measured values were consistent with the standard values, and the relative error (RE) was between -8. 33% and 7. 24%, indicating that this method was effective for the determination of rare earth elements. CONCLUSIONS: The method has simple operation, accurate and reliable results, and is suitable for the determination of rare earth elements in large quantities of uranium ore. [ABSTRACT FROM AUTHOR]