The waterborne polyurethane (WPU) emulsions were synthesized with toluene diisocyanates (TDI), poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA) and 1,4-butanediol (BDO) under acetone reflux，and characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and particle size distribution measurements. It shows that the particle size distribution of emulsion is 0.2-2.3 μm, the waterborne polyurethane resin degraded obviously at 263 ℃ and 379 ℃ attributes to the degradation of hard segment and soft segment respectively, which is an endothermic course. The scanning electron microscopy (SEM) images and FT-Raman spectra reveal that CL-20 is successfully coated by waterborne polyurethane. The impact sensitivity experimental results indicate that the characteristic height H₅₀ of CL-20 coated by WPU is increased by 40 percent.