||Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. Nowadays, the flame retardancy of polymers are the major concern. In this study, Polycarbonate (PC) was selected to develop an efficient flame retardant (FR) of high temperature polymer. A series of organo phosphorus flame retardants (FRs) based on aromatic phosphate and cyclic phosphate, mainly Biphenyl bis(cyclic 1,3-propanediol phosphate)(BP-CPP) and Biphenol bis(cyclic 2,2-dimethyl-1,3-propanediol phosphate)(BP-DMPP), were synthesized for polycarbonate. Their thermal stability and flame retarding efficiency as a single-component additive were investigated and compared with resorcinol bis(diphenyl phosphate) (RDP). Flame retarding efficiency was evaluated by the UL-94 test method. And its flame retarding performance was studied by the UL-94 and thermogravimetric analysis (TGA).