Phosphaphenanthrene (DOPO) derivatives were a kind of typical halogen-free organophosphorus flame retardants, which were also one of the research hotspots, exhibiting excellent flame retardant effect in both gaseous-phase and condensed-phase and improving the flame retardant performance of polymer materials. The characteristics, flame retardant mechanism, synthetic and application of phos-phaphe-nanthrene derivatives were described in thermoplastic resins (polyamide, polycarbonate, polyure-thane, ABS resin and polylactic acid) and thermosetting resins (epoxy resins and unsaturated polyester resin) in the past decade. Finally, the development trends of flame retardants were pointed out as follows: design of the molecules with high flame retardant performance; establish efficient synthesis method; pos-sess excellent mechanical properties.