To improve the thermionic emission performance of the rare-earth refractory yttrium salt cathode used in the magnetron, the influence of Sc₂O₃ doping on its thermionic emission properties was explored. Cathodes were fabricated by incorporating different weight percentages of Sc₂O₃ into the rare-earth refractory yttrium salt matrix, and their thermionic emission properties were systematically evaluated. The experimental findings revealed that the doping of Sc₂O₃ significantly enhances the thermionic emission capability of the cathode. Notably, a doping concentration of 3wt% Sc₂O₃ yielded the most pronounced improvement in emission performance. The 3wt% Sc₂O₃-doped cathode could achieve a thermionic emission current density of 3.85A/cm² under a 300 V anode voltage at 1600℃. In contrast, the undoped cathode supplied a current density of merely 1.66A/cm² under identical conditions, demonstrating a 132% enhancement in thermionic emission efficiency with 3wt% Sc₂O₃ doping. Utilizing the Richardson line method coupled with data-fitting algorithms, the absolute zero work functions for undoped and Sc₂O₃-doped cathodes (3wt%, 7wt%, and 11wt%) were determined to be 1.42, 0.93, 0.98, and 1.11 eV, respectively. Longevity assessments indicated that the 3wt% Sc₂O₃-doped cathode had been stable for over 4200 hours without significant degradation under an initial load of 0.5 A/cm² at 1400℃. Finaly, those cathodes had been analyzed by the XRD, SEM, EDS, AES respectively. The analysis results showed that during thermionic emission testing, the Sc₂O₃ and Y₂Hf₂O₇ had undergone substitutional solid solution reactions, forming the Sc_xY_(2-x)Hf₂O_[7+(3/2)x] solid solution. This process induced lattice distortion in the Y₂Hf₂O₇, placing it in a high-energy state and thereby reducing the work function on the cathode’s surface. Concurrently, Sc from Sc₂O₃ displaced Y within the Y₂Hf₂O₇ unit cells, with the displaced Y existing in a metallic form, which enhanced the electrical conductivity of the cathode's surface. Additionally, the Sc_xY_(2-x)Hf₂O_[7+(3/2)x] solid solution generated a substantial number of Vo²⁺ oxygen vacancies and free electrons, further augmenting surface conductivity. Collectively, these mechanisms contributed to a marked enhancement in the cathode's thermionic emission capacity.