Abstract: Epoxy resin is a kind of thermosetting resin. It is widely used in coatings, adhesives, electronic appliances, etc. because of its low shrinkage rate during the curing reaction, and excellent adhesion, corrosion resistance, mechanical properties and electrical insulation properties. Aerospace and other fields. However, the limiting oxygen index of epoxy resin is only 19.8%, which is flammable in the air, which greatly limits its application. 9,10-dihydro-9-oxa-10-phosphinphenanthrene-10-oxide (DOPO) is a phosphorus-based flame retardant. The P－H bond in its molecular structure is highly active and burns. During the process, no harmful gas is released, and the advantages of high flame retardancy have become a hot spot in domestic and foreign research. Based on the related literature of DOPO used for flame-retardant epoxy resin in domestic and foreign data in recent years, the research progress of the flame-retardant mechanism and synthesis method of DOPO epoxy resin is reviewed, and the future research direction of DOPO flame-retardant field is made.