In this study, the flame resistant foam materials made from polyurethane (PU) / polylactic acid (PLA) composite with different ratio of Tris (2-chloroethyl) phosphate (TCEP) /Antimony trioxide (Sb_2O_3). The effect of TCEP/Sb_2O_3 ratio on density, porous size, hardness, impact strength, stress-strain and compressional resilience of PU/PLA composite foam were researched. The fire resistant was measured by Limiting Oxygen Index(LOI) and vertical flammability testing, the degradation and thermal properties of foam materials were investigated by hydrolysis analysis, FTIR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). From results shown the density, hardness, impact strength and compressional resilience of PU/PLA foam decreased with the increase of Sb_2O_3 ratio. The LOI value, vertical combustion performance and thermal properties(Td, Tm) of foam materials were improved by adding complex flame retardant TCEP / Sb_2O_3. While TCEP / Sb2O3 ratio at 0.5 / 0.5, the synergistic effect can obtain the best performance for flameproof and thermal properties, the flame resistance measured up to UL94-1985 standard. In addition, the carbon dioxide and water were produced after PU/PLA degradation, so that had not new functional groups were shown by FTIR analysis for degraded PU/ PLA foam.