Abstract: With the increasing global demand for green and low-carbon energy, the importance of hydrogen energy as a clean, efficient, and sustainable energy carrier has become increasingly prominent. Alkaline water electrolysis (AWE) technology has become the mainstream method of large-scale production of green hydrogen due to its high technical maturity and significant cost effectiveness. However, the problem of hydrogen to oxygen (HTO) penetration in the alkaline electrolyzer becomes a key factor restricting the safety and efficiency improvement of this technology under low current density operating conditions. This paper provides a comprehensive review of the formation mechanism, key influencing factors, and effective control strategies of HTO in alkaline electrolysis cells and a theoretical basis and technical support for the optimization and development of hydrogen production technology from alkaline electrolysis water. The production of hydrogen from alkaline electrolysis of water involves complex electrochemical reactions and material transport phenomena. In the electrolysis process, hydrogen, as one of the products, penetrates to the anode side under certain conditions and mixes with oxygen to produce HTO. This process increases the insecurity of the system and also may trigger the safety protection device, leading to frequent shutdowns of the electrolyzer and seriously affecting the efficiency of hydrogen production. Therefore, it is highly significant to study the formation mechanism and control method of HTO thoroughly to improve the safety and economy of alkaline electrolytic cells. The formation of HTO is a complex process involving the coupling of multiple physical fields, including hydrogen diffusion across the membrane, alkali convection transport, electroosmotic drag effect, hydrogen supersaturation in the electrolyte, and the mixing cycle of cathode and anode electrolyte. Among these, the mixing cycle of the electrolyte is considered to be the dominant factor leading to the formation of HTO. Through the establishment of the corresponding mathematical model and experimental verification, this paper deeply analyzes the influence of these mechanisms on the concentration of HTO and points out that the lye mixing cycle plays an important role in the formation of HTO. In terms of the factors influencing HTO, this paper systematically summarizes the influence law of key parameters such as current density, system pressure, working temperature, alkali concentration, and alkali flow rate on HTO concentration. The results show that increasing the current density, decreasing the system pressure and operating temperature, and increasing the concentration of lye all help to reduce the HTO concentration. However, in practice, adjustment of these parameters is often constrained by multiple factors, so it needs to be considered comprehensively to develop an optimal control strategy. For the HTO control problem, this paper reviews the current main research progress and control methods. In terms of diaphragm materials, researchers have significantly improved the gas barrier performance and ion conductivity of the diaphragm by modifying the polyphenylene sulfide (PPS) membrane and developing the titanium dioxide composite membrane and other new diaphragm materials, thereby effectively reducing the concentration of HTO. As for the catalyst, although the improved catalyst has achieved remarkable results in the proton exchange membrane water electrolysis system, its application in the AWE system is limited. However, hydrogen permeation can still be reduced to some extent by methods such as adding surfactant to optimize bubble behavior. In addition, optimizing the electrolytic cell structure, introducing external environmental factors, and accurately controlling system parameters are also effective ways to control HTO. For example, the introduction of a functional thin interlayer between the electrode and the diaphragm, addition of a third electrode, and use of ultrasound or a magnetic field to promote bubble detachment can effectively reduce the supersaturation of hydrogen in the electrolyte, thereby reducing HTO formation. At the same time, through the adaptive control strategy for adjusting the system pressure, alkali flow rate, and other parameters accurately, the HTO concentration can be controlled within a safe range while also ensuring system efficiency. In particular, the lye separation cycle technique has proven to be one of the most direct and effective methods to control HTO. By separating the cathode and anode cycling lye, the cross penetration of hydrogen can be reduced significantly. Although the technology faces challenges such as imbalance of lye concentration, these problems can be solved effectively and stable operation of the system can be maintained by strategies such as switching cycle modes regularly. In summary, the control of HTO in the alkaline electrolyzer is a complex problem involving many factors. Future research should continue to explore efficient, low-cost, and easy to engineer HTO control strategies, such as combining artificial intelligence and machine learning technology to achieve accurate modeling and predictive control of electrolytic systems. At the same time, strengthening the research and development and testing of new diaphragm materials and efficient catalysts is also an important direction to promote the further development of hydrogen production technology from alkaline electrolysis water. Through continuous research and innovation, it is expected to overcome the HTO penetration problem in alkaline electrolytic cells, improve the safety of the system and efficiency of hydrogen production, and provide strong support for the sustainable development of the hydrogen energy industry.