GAP-ETPE/NC polymer blends were prepared using glycidyl azide polymer(GAP) based energetic thermoplastic elastomer(ETPE) and nitrocellulose(NC) with different mass ratios by solution blending process. The structure of the GAP-ETPE/NC polymer blends was characterized by fourier transform infrared spectroscopy(FT-IR) and wide X-ray diffraction(WXRD). The thermal and mechanical properties were investigated by dynamic mechanic analysis(DMA), universal testing machine, shore durometer, and thermogravimetric(TG) analysis. Results show that the prepared GAP-ETPE/NC polymer blends have typical features of azido-typed polyether-based polyurethane and nitrocellulose. Compared to NC, their structural compatibility and thermal stability are certainly improved. Besides, the degree of crystallinity and orientation is promoted with increasing of NC content, which increase the strength and modulus of polymer blends. Meanwhile, there are significant improvements of elongation and low-temperature mechanical properties with the increasing of the GAP-ETPE content. When the mass fraction between GAP-ETPE and NC decreases from 5/5 to 3/7, the tensile strength increases from 20.7 MPa to 39.2 MPa, while breaking elongation decreases from 141% to 40.6% for GAP-ETPE/NC polymer blends.