Abstract: Statistics from the International Conference on Electrical Research (CIGRE) show that SF₆ gas-insulated equipment has high operational reliability, whereas the failure rate of SF₆ gas-insulated equipment in operation is much higher than that of the IEC standard. Limited by the complex metal fully enclosed structure of SF₆ gas-insulated equipment and strong electromagnetic interference during operation, it is still a major technical challenge to effectively and accurately monitor the operating status of SF₆ gas-insulated equipment. Due to the partial strong electromagnetic energy and high temperature caused by latent insulation failure in the early stage of the equipment, SF₆ gas insulation presents different degrees of decomposition, and the decomposition products mainly include SO₂F₂, SOF₂, SO₂, H₂S, CO₂, CF₄, etc. Extracting the component characteristics reflecting the fault attributes based on the characteristics of SF₆ fault decomposition components and establishing an effective fault diagnosis method are effective technical means for monitoring the insulation condition of SF₆ gas-insulated equipment, which is attracting widespread attention from the power industry and scientific research institutes. Among them, improving the detection speed, sensitivity and anti-interference of SF₆ fault decomposition components is a key problem that industry scholars are trying to overcome, and a series of groundbreaking research progress have been made recently. This paper summarizes the research progress of fault diagnosis method of SF₆ gas-insulated equipment based on fault decomposition components, focuses on the breakthrough results of optical detection and chemical sensing detection of SF₆ decomposition components, and summarizes the difficulties that need to be solved in the application of this technology.