Abstract: Single crystal hexaboride LaB₆ has excellent hot electron emission performance and chemical stability. It is an ideal material for space thermionic cathode emission sources, which directly affects its emission efficiency and lifespan. With the demonstration of high-power and long-life space missions for space electric propulsion systems, the preparation technology of large size, low-cost, and high-purity single crystal LaB₆ is becoming increasingly important. Based on the research on the development process of LaB₆ matrix both domestically and internationally, combined with the preparation technology of single crystal LaB₆, aiming at the application requirements of space electric propulsion, the key technologies and difficulties in crystal preparation are analyzed. Some suggestions for the engineering development of single crystal LaB₆ are put forward.