It is critical to prepare modified starch material with high toughness and hydrophobicity in an environmentally friendly way. In this work, polyurethane prepolymer (PUP) was synthesized and mixed reactively with thermoplastic starches (TPS) in an intensive mixer to prepare modified TPS at various processing temperatures. The modified TPS materials were characterized. Results showed that the toughness and hydrophobicity of the modified TPS were significantly improved as compared to pure starch material, due to the strong interaction between starch and elastic polyurethane microparticles. Modified TPS processed at different temperatures (60-90 degrees C) showed similar morphologies, thermal behaviors, and tensile properties, indicating that structure/properties of the modified TPS were independent of the given processing temperatures. The formation of microparticles with a high amount of NCO groups and high reaction activity of each NCO group played important roles to improve the reaction efficiency, which weakened the dependence of the modification on the given processing temperatures.