Polyurethan elastomer(PUE) was synthesized by hydroxy-terminated polybutadiene(HTPB) and polytetramethylene ether glycols(PTMEG),2,4-toluene diisocyanate(TDI-100) and 2,4/2,6-diamino-3,5-dimethylthiotoluene(DADMT) as extender.The mechanical properties and structure of PUE were characterized,by DSC,DMA and TG,and the effects of ratio of HTPB/PTMEG and average molecular weight of HTPB on the PUE were investigated.The results show that the mechanical properties of PUE are up to a good level(tensile strength is 30.3MPa,tear strength is 99.8kN/m)when the mass ratio of HTPB and PTMEG is 1∶4.On the tanδ-T curve of PU0(0.8),the tanδ peak is located at-56.2 ℃,and tanδ values is lower than 0.08 above 0 ℃.This show that the dynamic performance of HTPB-based PUE is better than of PTMEG-based.And HTPB-based PUE has a higher thermal stability