Abstract: A novel flame retardant for polyurethane foam, DOPOFR was synthesized by the condensation of benzaldehyde with aniline and DOPO. Using above flame retardant and expandable graphite (EG), triethylphosphate and DOPOFR polyurethane foam was prepared. Chemical structure of DOPOFR was characterized with FTIR, 1HNMR spectra, and 31PNMR spectra. The thermal stability, flameretardant properties, and mechanical behavior of PUFs with different contents of DOPOFR were investigated by thermogravimetric analysis, limited oxygen index, and universal testing machine. It showed that DOPOFR could form more char when it was lighted and get excellent flame retardancy for PUFs. The 　limited oxygen index value reached 24.7 % with only 20 wt % of DOPOFR. The synergistic effect among EG, triethylphosphate, and DOPOFR could further increase the limited oxygen index to 32 %.