Abstract:Electron spin resonance (EPR) is a powerful technique to study the electron structure and dynamics of many materials with unpaired electrons ( paramagnetic materials). Nowadays, EPR has been widely applied in chemistry, material, radiation detection, biology, and quantum information processing. Compared with the X-Band EPR, the high frequency / field EPR ( HF-EPR) has the advantages of resolution, sensitivity, and initialization. This article is a concise introduction to the history, basic theory, instrumentation, and characteristics of the HF-EPR, and the emphasis on the application of HF-EPR in the research on spin qudits. The progress and future prospects of this analysis technique are also outlined. The HF-EPR could be used as a tool to implement the coherent manipulation of spin qudits, further paving the way toward quantum logic gate operation and quantum algorithm.