A series of thermoplastic polyurethane elastomers (TPU) with different fraction of hard segments based on poly(ethylene-propylene adipate) (PEPA)/ethylene oxide/tetrahydrofurancopolyether(PET）as soft segments were synthesized. The TPUs were characterized by GPC, FTIR and the tensile testing, and were used to coat the hexanitrohexaazaisowurtzitane (CL-20) by water suspension method. The coating effects were assessed by testing impact sensitivity , surface free energy and XPS .The results show that impact sensitivity of CL-20 coated with TPU is lowered and affected by fraction of hard segments of TPU. The coating effects of CL-20 is apparently related to the mechanical properties of TPU. The comprehensive properties of TPU with 50% hard segments content are optimum. The special height H₅₀ of CL-20 coated by this kind of TPU is 46.2 cm, which increase 23.9 cm than that before coating. The coating degree achieved as 68.13%.