Abstract: Photocatalytic antibacterial materials have been popularized and widely used in the disinfection of municipal water, the large-scale wastewater sterilization treatment of industry, and medical treatment. Their antibacterial theory has also been continuously studied and improved, and the reactive oxygen species (ROS) antibacterial mechanism has the highest acceptance by the public. The role of ROS is the main bactericidal mechanism of photocatalytic antibacterial agents, and it is also the mechanism explanation at the molecular level in the fields of organic pollutant degradation and biological pathology. ROS at an abnormal steady-state concentration attacks the organic structure outside the cell and enters the cell, causing oxidative stress reactions inside the cell and irreversible damage to the cell until apoptosis. Therefore, a systematic analysis of the production pathways, principle of action, and corresponding detection methods of active oxygen is of great importance for improving the antibacterial activity of photocatalytic antibacterial agents and exploring the antibacterial mechanism of active oxygen. First, this article introduces the production mechanism of active oxygen in photocatalytic materials and its antibacterial performance. Particularly, the modification method of constructing heterojunctions and introducing oxygen vacancies is the main way to increase active oxygen production. Second, this article summarizes the production process and mechanisms of the main ROS, such as the superoxide anion radical (·O_2^- ), hydrogen peroxide (H₂O₂), singlet oxygen (¹O₂), and the hydroxyl radical (·OH), as well as the antibacterial process. Detection methods are summarized for four ROS, including direct methods and indirect methods as well the specific and selective reaction principle of probe molecules with ROS. Furthermore, the influencing factors of the total concentration of ROS excited by photocatalytic materials are sorted out, and a modification direction for producing ROS is proposed. This paper proposes the problems existing in the research on the action mechanism of ROS and the deficiencies in the detection methods of ROS and their specific interaction with cells. It is suggested to carefully analyze the antibacterial mechanism of ROS at the biological component level under the guidance of the generation chain of ROS and the dynamic balance system of various ROS. Finally, suggestions are made on the design and application of active oxygen antibacterial materials, and the development prospects are addressed.