With the aim to explore the efficient application of microwave liquefied product, experiment on the synthesis of polyurethane (PU) with microwave liquefied product from corn stover instead of petrochemical polyol was carried out. The optimized synthetic process of PU was 0.30g foam blowing agent and isocyanate index 1.0. The biodegradable property of the composites was investigated by means of bury test which showed 18.71% degradation rate in six months. The thermal gravimetric analysis indicated four phases in the thermal pyrolysis of PU. All the results indicated microwave liquefied product from corn stover could be used for the production of PU foam while the material property was to be characterized and improved.