This paper reviews the theoretical and experimental researches on Argon Power Cycle (APC) engines. Hydrogen-fueled APC is an innovative power system for a high efficiency and zero emissions, which employs argon rather than nitrogen as a diluent. Due to the large specific heat ratio of argon, the thermodynamic efficiency of APC engines is significantly higher compared to conventional internal combustion engines. However, APC engines face the challenge of knock inhibition, especially when using hydrogen as a fuel. Therefore, this paper summarizes the strategies and technologies to suppress the knock of hydrogen-fueled APC engines, including using alternative fuels with greater anti-knock capacity, lean combustion, and water injection. Furthermore, some guidance opinions are also provided for reference about the development and industrialization of APC engines, such as ultra-lean combustion, which uses pistons with thermal insulation coatings, employing low-friction lubricants, and developing efficient multi-component membrane separation system for argon separation.